sequence_id
string | sequence_name
string | sequence_first_terms
list | sequence_next_term
string | is_easy
int64 |
|---|---|---|---|---|
A000001
|
Number of groups of order n.
|
[
"0",
"1",
"1",
"1",
"2",
"1",
"2",
"1",
"5",
"2",
"2",
"1",
"5",
"1",
"2",
"1",
"14",
"1",
"5"
] |
1
| 0
|
A000002
|
Kolakoski sequence: a(n) is length of n-th run; a(1) = 1; sequence consists just of 1's and 2's.
|
[
"1",
"2",
"2",
"1",
"1",
"2",
"1",
"2",
"2",
"1",
"2",
"2",
"1",
"1",
"2",
"1",
"1",
"2",
"2"
] |
1
| 1
|
A000003
|
Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.
|
[
"1",
"1",
"1",
"1",
"2",
"2",
"1",
"2",
"2",
"2",
"3",
"2",
"2",
"4",
"2",
"2",
"4",
"2",
"3"
] |
4
| 1
|
A000004
|
The zero sequence.
|
[
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0"
] |
0
| 1
|
A000005
|
d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.
|
[
"1",
"2",
"2",
"3",
"2",
"4",
"2",
"4",
"3",
"4",
"2",
"6",
"2",
"4",
"4",
"5",
"2",
"6",
"2"
] |
6
| 1
|
A000006
|
Integer part of square root of n-th prime.
|
[
"1",
"1",
"2",
"2",
"3",
"3",
"4",
"4",
"4",
"5",
"5",
"6",
"6",
"6",
"6",
"7",
"7",
"7",
"8"
] |
8
| 1
|
A000007
|
The characteristic function of {0}: a(n) = 0^n.
|
[
"1",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0"
] |
0
| 1
|
A000008
|
Number of ways of making change for n cents using coins of 1, 2, 5, 10 cents.
|
[
"1",
"1",
"2",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"11",
"12",
"15",
"16",
"19",
"22",
"25",
"28",
"31"
] |
34
| 1
|
A000009
|
Expansion of Product_{m >= 1} (1 + x^m); number of partitions of n into distinct parts; number of partitions of n into odd parts.
|
[
"1",
"1",
"1",
"2",
"2",
"3",
"4",
"5",
"6",
"8",
"10",
"12",
"15",
"18",
"22",
"27",
"32",
"38",
"46"
] |
54
| 1
|
A000010
|
Euler totient function phi(n): count numbers <= n and prime to n.
|
[
"1",
"1",
"2",
"2",
"4",
"2",
"6",
"4",
"6",
"4",
"10",
"4",
"12",
"6",
"8",
"8",
"16",
"6",
"18"
] |
8
| 1
|
A000011
|
Number of n-bead necklaces (turning over is allowed) where complements are equivalent.
|
[
"1",
"1",
"2",
"2",
"4",
"4",
"8",
"9",
"18",
"23",
"44",
"63",
"122",
"190",
"362",
"612",
"1162",
"2056",
"3914"
] |
7155
| 1
|
A000012
|
The simplest sequence of positive numbers: the all 1's sequence.
|
[
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1"
] |
1
| 1
|
A000013
|
Definition (1): Number of n-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed.
|
[
"1",
"1",
"2",
"2",
"4",
"4",
"8",
"10",
"20",
"30",
"56",
"94",
"180",
"316",
"596",
"1096",
"2068",
"3856",
"7316"
] |
13798
| 1
|
A000014
|
Number of series-reduced trees with n nodes.
|
[
"0",
"1",
"1",
"0",
"1",
"1",
"2",
"2",
"4",
"5",
"10",
"14",
"26",
"42",
"78",
"132",
"249",
"445",
"842"
] |
1561
| 1
|
A000015
|
Smallest prime power >= n.
|
[
"1",
"2",
"3",
"4",
"5",
"7",
"7",
"8",
"9",
"11",
"11",
"13",
"13",
"16",
"16",
"16",
"17",
"19",
"19"
] |
23
| 1
|
A000016
|
a(n) is the number of distinct (infinite) output sequences from binary n-stage shift register which feeds back the complement of the last stage.
|
[
"1",
"1",
"1",
"2",
"2",
"4",
"6",
"10",
"16",
"30",
"52",
"94",
"172",
"316",
"586",
"1096",
"2048",
"3856",
"7286"
] |
13798
| 1
|
A000017
|
Erroneous version of A032522.
|
[
"1",
"0",
"0",
"2",
"2",
"4",
"8",
"4",
"16",
"12",
"48",
"80",
"136",
"420",
"1240",
"2872",
"7652",
"18104"
] |
50184
| 0
|
A000018
|
Number of positive integers <= 2^n of form x^2 + 16*y^2.
|
[
"1",
"1",
"2",
"2",
"4",
"8",
"13",
"25",
"44",
"83",
"152",
"286",
"538",
"1020",
"1942",
"3725",
"7145",
"13781",
"26627"
] |
51572
| 0
|
A000019
|
Number of primitive permutation groups of degree n.
|
[
"1",
"1",
"2",
"2",
"5",
"4",
"7",
"7",
"11",
"9",
"8",
"6",
"9",
"4",
"6",
"22",
"10",
"4",
"8"
] |
4
| 0
|
A000020
|
Number of primitive polynomials of degree n over GF(2) (version 2).
|
[
"2",
"1",
"2",
"2",
"6",
"6",
"18",
"16",
"48",
"60",
"176",
"144",
"630",
"756",
"1800",
"2048",
"7710",
"7776",
"27594"
] |
24000
| 0
|
A000021
|
Number of positive integers <= 2^n of form x^2 + 12 y^2.
|
[
"1",
"1",
"2",
"2",
"6",
"9",
"17",
"30",
"54",
"98",
"183",
"341",
"645",
"1220",
"2327",
"4451",
"8555",
"16489",
"31859"
] |
61717
| 0
|
A000022
|
Number of centered hydrocarbons with n atoms.
|
[
"0",
"1",
"0",
"1",
"1",
"2",
"2",
"6",
"9",
"20",
"37",
"86",
"181",
"422",
"943",
"2223",
"5225",
"12613",
"30513"
] |
74883
| 1
|
A000023
|
Expansion of e.g.f. exp(-2*x)/(1-x).
|
[
"1",
"-1",
"2",
"-2",
"8",
"8",
"112",
"656",
"5504",
"49024",
"491264",
"5401856",
"64826368",
"842734592",
"11798300672",
"176974477312",
"2831591702528",
"48137058811904",
"866467058876416"
] |
16462874118127616
| 1
|
A000024
|
Number of positive integers <= 2^n of form x^2 + 10 y^2.
|
[
"1",
"1",
"2",
"2",
"7",
"10",
"20",
"36",
"65",
"118",
"221",
"409",
"776",
"1463",
"2788",
"5328",
"10222",
"19714",
"38054"
] |
73685
| 0
|
A000025
|
Coefficients of the 3rd-order mock theta function f(q).
|
[
"1",
"1",
"-2",
"3",
"-3",
"3",
"-5",
"7",
"-6",
"6",
"-10",
"12",
"-11",
"13",
"-17",
"20",
"-21",
"21",
"-27"
] |
34
| 1
|
A000026
|
Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).
|
[
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"6",
"6",
"10",
"11",
"12",
"13",
"14",
"15",
"8",
"17",
"12",
"19"
] |
20
| 1
|
A000027
|
The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.
|
[
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"10",
"11",
"12",
"13",
"14",
"15",
"16",
"17",
"18",
"19"
] |
20
| 1
|
A000028
|
Let k = p_1^e_1 p_2^e_2 p_3^e_3 ... be the prime factorization of n. Sequence gives k such that the sum of the numbers of 1's in the binary expansions of e_1, e_2, e_3, ... is odd.
|
[
"2",
"3",
"4",
"5",
"7",
"9",
"11",
"13",
"16",
"17",
"19",
"23",
"24",
"25",
"29",
"30",
"31",
"37",
"40"
] |
41
| 1
|
A000029
|
Number of necklaces with n beads of 2 colors, allowing turning over (these are also called bracelets).
|
[
"1",
"2",
"3",
"4",
"6",
"8",
"13",
"18",
"30",
"46",
"78",
"126",
"224",
"380",
"687",
"1224",
"2250",
"4112",
"7685"
] |
14310
| 1
|
A000030
|
Initial digit of n.
|
[
"0",
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1"
] |
1
| 1
|
A000031
|
Number of n-bead necklaces with 2 colors when turning over is not allowed; also number of output sequences from a simple n-stage cycling shift register; also number of binary irreducible polynomials whose degree divides n.
|
[
"1",
"2",
"3",
"4",
"6",
"8",
"14",
"20",
"36",
"60",
"108",
"188",
"352",
"632",
"1182",
"2192",
"4116",
"7712",
"14602"
] |
27596
| 1
|
A000032
|
Lucas numbers beginning at 2: L(n) = L(n-1) + L(n-2), L(0) = 2, L(1) = 1.
|
[
"2",
"1",
"3",
"4",
"7",
"11",
"18",
"29",
"47",
"76",
"123",
"199",
"322",
"521",
"843",
"1364",
"2207",
"3571",
"5778"
] |
9349
| 1
|
A000033
|
Coefficients of ménage hit polynomials.
|
[
"0",
"2",
"3",
"4",
"40",
"210",
"1477",
"11672",
"104256",
"1036050",
"11338855",
"135494844",
"1755206648",
"24498813794",
"366526605705",
"5851140525680",
"99271367764480",
"1783734385752162",
"33837677493828171"
] |
675799125332580020
| 1
|
A000034
|
Period 2: repeat [1, 2]; a(n) = 1 + (n mod 2).
|
[
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1"
] |
2
| 1
|
A000035
|
Period 2: repeat [0, 1]; a(n) = n mod 2; parity of n.
|
[
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0",
"1",
"0"
] |
1
| 1
|
A000036
|
Let A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); A000099 gives values of n where |P(n)| sets a new record; sequence gives closest integer to P(A000099(n)).
|
[
"2",
"3",
"5",
"6",
"6",
"-6",
"7",
"8",
"10",
"13",
"13",
"13",
"14",
"-17",
"17",
"17",
"18",
"-19",
"20"
] |
-22
| 0
|
A000037
|
Numbers that are not squares (or, the nonsquares).
|
[
"2",
"3",
"5",
"6",
"7",
"8",
"10",
"11",
"12",
"13",
"14",
"15",
"17",
"18",
"19",
"20",
"21",
"22",
"23"
] |
24
| 1
|
A000038
|
Twice A000007.
|
[
"2",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0",
"0"
] |
0
| 1
|
A000039
|
Coefficient of q^(2n) in the series expansion of Ramanujan's mock theta function f(q).
|
[
"1",
"-2",
"-3",
"-5",
"-6",
"-10",
"-11",
"-17",
"-21",
"-27",
"-33",
"-46",
"-53",
"-68",
"-82",
"-104",
"-123",
"-154",
"-179"
] |
-221
| 0
|
A000040
|
The prime numbers.
|
[
"2",
"3",
"5",
"7",
"11",
"13",
"17",
"19",
"23",
"29",
"31",
"37",
"41",
"43",
"47",
"53",
"59",
"61",
"67"
] |
71
| 1
|
A000041
|
a(n) is the number of partitions of n (the partition numbers).
|
[
"1",
"1",
"2",
"3",
"5",
"7",
"11",
"15",
"22",
"30",
"42",
"56",
"77",
"101",
"135",
"176",
"231",
"297",
"385"
] |
490
| 1
|
A000042
|
Unary representation of natural numbers.
|
[
"1",
"11",
"111",
"1111",
"11111",
"111111",
"1111111",
"11111111",
"111111111",
"1111111111",
"11111111111",
"111111111111",
"1111111111111",
"11111111111111",
"111111111111111",
"1111111111111111",
"11111111111111111",
"111111111111111111",
"1111111111111111111"
] |
11111111111111111111
| 1
|
A000043
|
Mersenne exponents: primes p such that 2^p - 1 is prime. Then 2^p - 1 is called a Mersenne prime.
|
[
"2",
"3",
"5",
"7",
"13",
"17",
"19",
"31",
"61",
"89",
"107",
"127",
"521",
"607",
"1279",
"2203",
"2281",
"3217",
"4253"
] |
4423
| 0
|
A000044
|
Dying rabbits: a(0) = 1; for 1 <= n <= 12, a(n) = Fibonacci(n); for n >= 13, a(n) = a(n-1) + a(n-2) - a(n-13).
|
[
"1",
"1",
"1",
"2",
"3",
"5",
"8",
"13",
"21",
"34",
"55",
"89",
"144",
"232",
"375",
"606",
"979",
"1582",
"2556"
] |
4130
| 1
|
A000045
|
Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1.
|
[
"0",
"1",
"1",
"2",
"3",
"5",
"8",
"13",
"21",
"34",
"55",
"89",
"144",
"233",
"377",
"610",
"987",
"1597",
"2584"
] |
4181
| 1
|
A000046
|
Number of primitive n-bead necklaces (turning over is allowed) where complements are equivalent.
|
[
"1",
"1",
"1",
"1",
"2",
"3",
"5",
"8",
"14",
"21",
"39",
"62",
"112",
"189",
"352",
"607",
"1144",
"2055",
"3885"
] |
7154
| 1
|
A000047
|
Number of integers <= 2^n of form x^2 - 2y^2.
|
[
"1",
"2",
"3",
"5",
"8",
"15",
"26",
"48",
"87",
"161",
"299",
"563",
"1066",
"2030",
"3885",
"7464",
"14384",
"27779",
"53782"
] |
104359
| 0
|
A000048
|
Number of n-bead necklaces with beads of 2 colors and primitive period n, when turning over is not allowed but the two colors can be interchanged.
|
[
"1",
"1",
"1",
"1",
"2",
"3",
"5",
"9",
"16",
"28",
"51",
"93",
"170",
"315",
"585",
"1091",
"2048",
"3855",
"7280"
] |
13797
| 1
|
A000049
|
Number of positive integers <= 2^n of the form 3*x^2 + 4*y^2.
|
[
"0",
"0",
"2",
"3",
"5",
"9",
"16",
"29",
"53",
"98",
"181",
"341",
"640",
"1218",
"2321",
"4449",
"8546",
"16482",
"31845"
] |
61707
| 0
|
A000050
|
Number of positive integers <= 2^n of form x^2 + y^2.
|
[
"1",
"2",
"3",
"5",
"9",
"16",
"29",
"54",
"97",
"180",
"337",
"633",
"1197",
"2280",
"4357",
"8363",
"16096",
"31064",
"60108"
] |
116555
| 0
|
A000051
|
a(n) = 2^n + 1.
|
[
"2",
"3",
"5",
"9",
"17",
"33",
"65",
"129",
"257",
"513",
"1025",
"2049",
"4097",
"8193",
"16385",
"32769",
"65537",
"131073",
"262145"
] |
524289
| 1
|
A000052
|
1-digit numbers arranged in alphabetical order, then the 2-digit numbers arranged in alphabetical order, then the 3-digit numbers, etc.
|
[
"8",
"5",
"4",
"9",
"1",
"7",
"6",
"3",
"2",
"0",
"18",
"80",
"88",
"85",
"84",
"89",
"81",
"87",
"86"
] |
83
| 0
|
A000053
|
Local stops on New York City 1 Train (Broadway-7 Avenue Local) subway.
|
[
"14",
"18",
"23",
"28",
"34",
"42",
"50",
"59",
"66",
"72",
"79",
"86",
"96",
"103",
"110",
"116",
"125",
"137",
"145"
] |
157
| 0
|
A000054
|
Local stops on New York City A line subway.
|
[
"4",
"14",
"23",
"34",
"42",
"50",
"59",
"72",
"81",
"86",
"96",
"103",
"110",
"116",
"125",
"135",
"145",
"155",
"163"
] |
168
| 0
|
A000055
|
Number of trees with n unlabeled nodes.
|
[
"1",
"1",
"1",
"1",
"2",
"3",
"6",
"11",
"23",
"47",
"106",
"235",
"551",
"1301",
"3159",
"7741",
"19320",
"48629",
"123867"
] |
317955
| 1
|
A000056
|
Order of the group SL(2,Z_n).
|
[
"1",
"6",
"24",
"48",
"120",
"144",
"336",
"384",
"648",
"720",
"1320",
"1152",
"2184",
"2016",
"2880",
"3072",
"4896",
"3888",
"6840"
] |
5760
| 1
|
A000057
|
Primes dividing all Fibonacci sequences.
|
[
"2",
"3",
"7",
"23",
"43",
"67",
"83",
"103",
"127",
"163",
"167",
"223",
"227",
"283",
"367",
"383",
"443",
"463",
"467"
] |
487
| 0
|
A000058
|
Sylvester's sequence: a(n+1) = a(n)^2 - a(n) + 1, with a(0) = 2.
|
[
"2",
"3",
"7",
"43",
"1807",
"3263443",
"10650056950807",
"113423713055421844361000443"
] |
12864938683278671740537145998360961546653259485195807
| 0
|
A000059
|
Numbers k such that (2k)^4 + 1 is prime.
|
[
"1",
"2",
"3",
"8",
"10",
"12",
"14",
"17",
"23",
"24",
"27",
"28",
"37",
"40",
"41",
"44",
"45",
"53",
"59"
] |
66
| 1
|
A000060
|
Number of signed trees with n nodes.
|
[
"1",
"2",
"3",
"10",
"27",
"98",
"350",
"1402",
"5743",
"24742",
"108968",
"492638",
"2266502",
"10600510",
"50235931",
"240882152",
"1166732814",
"5702046382",
"28088787314"
] |
139355139206
| 0
|
A000061
|
Generalized tangent numbers d(n,1).
|
[
"1",
"1",
"2",
"4",
"4",
"6",
"8",
"8",
"12",
"14",
"14",
"16",
"20",
"20",
"24",
"32",
"24",
"30",
"38"
] |
32
| 0
|
A000062
|
A Beatty sequence: a(n) = floor(n/(e-2)).
|
[
"1",
"2",
"4",
"5",
"6",
"8",
"9",
"11",
"12",
"13",
"15",
"16",
"18",
"19",
"20",
"22",
"23",
"25",
"26"
] |
27
| 0
|
A000063
|
Symmetrical dissections of an n-gon.
|
[
"1",
"1",
"2",
"4",
"5",
"14",
"14",
"39",
"42",
"132",
"132",
"424",
"429",
"1428",
"1430",
"4848",
"4862",
"16796",
"16796"
] |
58739
| 0
|
A000064
|
Partial sums of (unordered) ways of making change for n cents using coins of 1, 2, 5, 10 cents.
|
[
"1",
"2",
"4",
"6",
"9",
"13",
"18",
"24",
"31",
"39",
"50",
"62",
"77",
"93",
"112",
"134",
"159",
"187",
"218"
] |
252
| 1
|
A000065
|
-1 + number of partitions of n.
|
[
"0",
"0",
"1",
"2",
"4",
"6",
"10",
"14",
"21",
"29",
"41",
"55",
"76",
"100",
"134",
"175",
"230",
"296",
"384"
] |
489
| 1
|
A000066
|
Smallest number of vertices in trivalent graph with girth (shortest cycle) = n.
|
[
"4",
"6",
"10",
"14",
"24",
"30",
"58",
"70",
"112"
] |
126
| 0
|
A000067
|
Number of positive integers <= 2^n of form x^2 + 2 y^2.
|
[
"1",
"2",
"4",
"6",
"10",
"18",
"33",
"60",
"111",
"205",
"385",
"725",
"1374",
"2610",
"4993",
"9578",
"18426",
"35568",
"68806"
] |
133411
| 0
|
A000068
|
Numbers k such that k^4 + 1 is prime.
|
[
"1",
"2",
"4",
"6",
"16",
"20",
"24",
"28",
"34",
"46",
"48",
"54",
"56",
"74",
"80",
"82",
"88",
"90",
"106"
] |
118
| 1
|
A000069
|
Odious numbers: numbers with an odd number of 1's in their binary expansion.
|
[
"1",
"2",
"4",
"7",
"8",
"11",
"13",
"14",
"16",
"19",
"21",
"22",
"25",
"26",
"28",
"31",
"32",
"35",
"37"
] |
38
| 1
|
A000070
|
a(n) = Sum_{k=0..n} p(k) where p(k) = number of partitions of k (A000041).
|
[
"1",
"2",
"4",
"7",
"12",
"19",
"30",
"45",
"67",
"97",
"139",
"195",
"272",
"373",
"508",
"684",
"915",
"1212",
"1597"
] |
2087
| 1
|
A000071
|
a(n) = Fibonacci(n) - 1.
|
[
"0",
"0",
"1",
"2",
"4",
"7",
"12",
"20",
"33",
"54",
"88",
"143",
"232",
"376",
"609",
"986",
"1596",
"2583",
"4180"
] |
6764
| 1
|
A000072
|
Number of positive integers <= 2^n of form x^2 + 4 y^2.
|
[
"1",
"1",
"2",
"4",
"7",
"12",
"22",
"41",
"72",
"137",
"254",
"476",
"901",
"1716",
"3274",
"6286",
"12090",
"23331",
"45140"
] |
87511
| 0
|
A000073
|
Tribonacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) for n >= 3 with a(0) = a(1) = 0 and a(2) = 1.
|
[
"0",
"0",
"1",
"1",
"2",
"4",
"7",
"13",
"24",
"44",
"81",
"149",
"274",
"504",
"927",
"1705",
"3136",
"5768",
"10609"
] |
19513
| 1
|
A000074
|
Number of odd integers <= 2^n of form x^2 + y^2.
|
[
"1",
"1",
"2",
"4",
"7",
"13",
"25",
"43",
"83",
"157",
"296",
"564",
"1083",
"2077",
"4006",
"7733",
"14968",
"29044",
"56447"
] |
109864
| 0
|
A000075
|
Number of positive integers <= 2^n of form 2 x^2 + 3 y^2.
|
[
"0",
"1",
"2",
"4",
"7",
"14",
"23",
"42",
"76",
"139",
"258",
"482",
"907",
"1717",
"3269",
"6257",
"12020",
"23171",
"44762"
] |
86683
| 0
|
A000076
|
Number of integers <= 2^n of form 4 x^2 + 4 x y + 5 y^2.
|
[
"0",
"0",
"1",
"2",
"4",
"7",
"14",
"24",
"43",
"82",
"149",
"284",
"534",
"1015",
"1937",
"3713",
"7136",
"13759",
"26597"
] |
51537
| 0
|
A000077
|
Number of positive integers <= 2^n of form x^2 + 6 y^2.
|
[
"1",
"1",
"2",
"4",
"8",
"13",
"24",
"42",
"76",
"140",
"257",
"483",
"907",
"1717",
"3272",
"6261",
"12027",
"23172",
"44769"
] |
86708
| 0
|
A000078
|
Tetranacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) for n >= 4 with a(0) = a(1) = a(2) = 0 and a(3) = 1.
|
[
"0",
"0",
"0",
"1",
"1",
"2",
"4",
"8",
"15",
"29",
"56",
"108",
"208",
"401",
"773",
"1490",
"2872",
"5536",
"10671"
] |
20569
| 1
|
A000079
|
Powers of 2: a(n) = 2^n.
|
[
"1",
"2",
"4",
"8",
"16",
"32",
"64",
"128",
"256",
"512",
"1024",
"2048",
"4096",
"8192",
"16384",
"32768",
"65536",
"131072",
"262144"
] |
524288
| 1
|
A000080
|
Number of nonisomorphic minimal triangle graphs.
|
[
"1",
"1",
"2",
"4",
"9",
"19",
"48",
"117",
"307",
"821",
"2277",
"6437",
"18634",
"54775",
"163703",
"495529",
"1518706",
"4703848",
"14714754"
] |
46444979
| 0
|
A000081
|
Number of unlabeled rooted trees with n nodes (or connected functions with a fixed point).
|
[
"0",
"1",
"1",
"2",
"4",
"9",
"20",
"48",
"115",
"286",
"719",
"1842",
"4766",
"12486",
"32973",
"87811",
"235381",
"634847",
"1721159"
] |
4688676
| 1
|
A000082
|
a(n) = n^2*Product_{p|n} (1 + 1/p).
|
[
"1",
"6",
"12",
"24",
"30",
"72",
"56",
"96",
"108",
"180",
"132",
"288",
"182",
"336",
"360",
"384",
"306",
"648",
"380"
] |
720
| 1
|
A000083
|
Number of mixed Husimi trees with n nodes; or polygonal cacti with bridges.
|
[
"1",
"1",
"1",
"2",
"4",
"9",
"23",
"63",
"188",
"596",
"1979",
"6804",
"24118",
"87379",
"322652",
"1209808",
"4596158",
"17657037",
"68497898"
] |
268006183
| 0
|
A000084
|
Number of series-parallel networks with n unlabeled edges. Also called yoke-chains by Cayley and MacMahon.
|
[
"1",
"2",
"4",
"10",
"24",
"66",
"180",
"522",
"1532",
"4624",
"14136",
"43930",
"137908",
"437502",
"1399068",
"4507352",
"14611576",
"47633486",
"156047204"
] |
513477502
| 1
|
A000085
|
Number of self-inverse permutations on n letters, also known as involutions; number of standard Young tableaux with n cells.
|
[
"1",
"1",
"2",
"4",
"10",
"26",
"76",
"232",
"764",
"2620",
"9496",
"35696",
"140152",
"568504",
"2390480",
"10349536",
"46206736",
"211799312",
"997313824"
] |
4809701440
| 1
|
A000086
|
Number of solutions to x^2 - x + 1 == 0 (mod n).
|
[
"1",
"0",
"1",
"0",
"0",
"0",
"2",
"0",
"0",
"0",
"0",
"0",
"2",
"0",
"0",
"0",
"0",
"0",
"2"
] |
0
| 1
|
A000087
|
Number of unrooted nonseparable planar maps with n edges and a distinguished face.
|
[
"2",
"1",
"2",
"4",
"10",
"37",
"138",
"628",
"2972",
"14903",
"76994",
"409594",
"2222628",
"12281570",
"68864086",
"391120036",
"2246122574",
"13025721601",
"76194378042"
] |
449155863868
| 0
|
A000088
|
Number of simple graphs on n unlabeled nodes.
|
[
"1",
"1",
"2",
"4",
"11",
"34",
"156",
"1044",
"12346",
"274668",
"12005168",
"1018997864",
"165091172592",
"50502031367952",
"29054155657235488",
"31426485969804308768",
"64001015704527557894928",
"245935864153532932683719776",
"1787577725145611700547878190848"
] |
24637809253125004524383007491432768
| 0
|
A000089
|
Number of solutions to x^2 + 1 == 0 (mod n).
|
[
"1",
"1",
"0",
"0",
"2",
"0",
"0",
"0",
"0",
"2",
"0",
"0",
"2",
"0",
"0",
"0",
"2",
"0",
"0"
] |
0
| 0
|
A000090
|
Expansion of e.g.f. exp((-x^3)/3)/(1-x).
|
[
"1",
"1",
"2",
"4",
"16",
"80",
"520",
"3640",
"29120",
"259840",
"2598400",
"28582400",
"343235200",
"4462057600",
"62468806400",
"936987251200",
"14991796019200",
"254860532326400",
"4587501779660800"
] |
87162533813555200
| 1
|
A000091
|
Multiplicative with a(2^e) = 2 for k >= 1; a(3) = 2, a(3^e) = 0 for k >= 2; a(p^e) = 0 if p > 3 and p == -1 (mod 3); a(p^e) = 2 if p > 3 and p == 1 (mod 3).
|
[
"1",
"2",
"2",
"2",
"0",
"4",
"2",
"2",
"0",
"0",
"0",
"4",
"2",
"4",
"0",
"2",
"0",
"0",
"2"
] |
0
| 1
|
A000092
|
Let A(n) = #{(i,j,k): i^2 + j^2 + k^2 <= n}, V(n) = (4/3)Pi*n^(3/2), P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.
|
[
"1",
"2",
"5",
"6",
"14",
"21",
"29",
"30",
"54",
"90",
"134",
"155",
"174",
"230",
"234",
"251",
"270",
"342",
"374"
] |
461
| 0
|
A000093
|
a(n) = floor(n^(3/2)).
|
[
"0",
"1",
"2",
"5",
"8",
"11",
"14",
"18",
"22",
"27",
"31",
"36",
"41",
"46",
"52",
"58",
"64",
"70",
"76"
] |
82
| 1
|
A000094
|
Number of trees of diameter 4.
|
[
"0",
"0",
"0",
"0",
"1",
"2",
"5",
"8",
"14",
"21",
"32",
"45",
"65",
"88",
"121",
"161",
"215",
"280",
"367"
] |
471
| 0
|
A000095
|
Number of fixed points of GAMMA_0 (n) of type i.
|
[
"1",
"2",
"0",
"0",
"2",
"0",
"0",
"0",
"0",
"4",
"0",
"0",
"2",
"0",
"0",
"0",
"2",
"0",
"0"
] |
0
| 1
|
A000096
|
a(n) = n*(n+3)/2.
|
[
"0",
"2",
"5",
"9",
"14",
"20",
"27",
"35",
"44",
"54",
"65",
"77",
"90",
"104",
"119",
"135",
"152",
"170",
"189"
] |
209
| 1
|
A000097
|
Number of partitions of n if there are two kinds of 1's and two kinds of 2's.
|
[
"1",
"2",
"5",
"9",
"17",
"28",
"47",
"73",
"114",
"170",
"253",
"365",
"525",
"738",
"1033",
"1422",
"1948",
"2634",
"3545"
] |
4721
| 1
|
A000098
|
Number of partitions of n if there are two kinds of 1, two kinds of 2 and two kinds of 3.
|
[
"1",
"2",
"5",
"10",
"19",
"33",
"57",
"92",
"147",
"227",
"345",
"512",
"752",
"1083",
"1545",
"2174",
"3031",
"4179",
"5719"
] |
7752
| 1
|
A000099
|
Let A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.
|
[
"1",
"2",
"5",
"10",
"20",
"24",
"26",
"41",
"53",
"130",
"149",
"205",
"234",
"287",
"340",
"410",
"425",
"480",
"586"
] |
840
| 0
|
A000100
|
a(n) is the number of compositions of n in which the maximal part is 3.
|
[
"0",
"0",
"0",
"1",
"2",
"5",
"11",
"23",
"47",
"94",
"185",
"360",
"694",
"1328",
"2526",
"4781",
"9012",
"16929",
"31709"
] |
59247
| 1
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.