Number of ways of selecting $n$ things out of $3n$ things, of which $n$ are of one kind alike, $n$ of second type are alike, and rest are different
12046
No. of ways to choose $n$ things from $n$ alike "a" things $n$ alike "b" things and $n$ different things.
88356
Number of options to distribute $N$ different balls to $K$ numbered cells
134352
The number of possible factorizations of a positive integer.
73323
Permutations when some objects are alike
98991
How many different spanning trees of $K_n \setminus e$ are there?
107010
How many elements of order $k$ are in $S_n$?
57954
How many transitive relations on a set of $n$ elements?
142477
Closed-form expression for the number of $k$-permutations of length $n$. Duplicates allowed!
43979
The total number of subsets is $2^n$ for $n$ elements
9009
$n$ choose $k$ where $n$ is less than $k$
98313
Number of possible permutations of n1 1's, n2 2's, n3 3's, n4 4's such that no two adjacent elements are same?
122504
Factorisations of permutations
9971
enumerative combinatorics,In how many ways (as a function of n) can one choose a composition α α of n
17580
Combinatorics That Looks Similar to Vandermonde's Identity
153072
Guessing a subset of $\{1,...,N\}$
45074
Combinatorics: Selecting objects arranged in a circle
34452
In how many ways can you choose $k$ numbers out of $\{1,2,3,\dots,n\}$ so none of them is consecutive?