For a set with N members, what is the number of set partitions in which each subset is either of size 1 or 2?
123137
Recursion: putting people into groups of 1 or 2
113668
Uncountable chain of subsets of $\mathbb N$
104010
The number of partitions of $n$ into distinct parts equals the number of partitions of $n$ into odd parts
3392
Sum of products of elements of nonempty subsets of A set
31969
Partition of N into infinite number of infinite disjoint sets?
11849
Size of a union of two sets
124060
Are these subsets of the powerset P(N) countable?
26569
Counting binary operations on a set with $n$ elements
135698
Count subsets whose cardinalities are congruent to 0, 1 and 2 modulo 3 respectively
85099
How many subsets of $\mathbb{N}$ have the same cardinality as $\mathbb{N}$?
36486
Finding the total number of set-bits from 1 to n
73224
number of ordered partitions of integer
113980
Prove that a set of nine consecutive integers cannot be partitioned into two subsets with same product
7785
Cardinality of sum-set
25338
Sum of $n$ integers from set of size $2n-1$ divides $n$
117434
Counting integer partitions of n into exactly k distinct parts size at most M
92941
# of partitions of $n$ into at most $r$ positive integers $=$ # of partitions of $n + r$ into exactly $r$ positive integers?