Number of ways to connect sets of k vertices in a perfect n-gon
70761
Number of ways to connect sets of $k$ dots in a perfect $n$-gon
8458
Combinatorics problem based on Ferrers graph
72052
Combinatorics the number of options for $k$ different balls in n different cells, with at least $1$ ball in each cell
63379
Enumerate non-isomorphic graphs on n vertices
17086
The number of (non-equal) forests on the vertex set V = {1, 2, ...,n} that contains exactly 2 connected components is given by
1627
Cartesian product of an arbitrary number of sets
111324
Finding number of relations on a set with 3 elements
40852
Number of ways of distributing $n$ identical objects among $r$ groups
96086
Double Factorial: Number of possibilities to partition a set of $2n$ items into $n$ pairs
93748
Alternative to Subsets to generate k-combinations
117349
counting triangles in a graph or its complement
26343
Number of certain (0,1)-matrices, Stanley's Enumerative Combinatorics
92554
How many lattice paths are there from $(0,0)$ to $(2n,2n)$ that avoids odd points
117020
Regular $n$-gon in the plane with vertices on integers?
134938
Committee combinatorics
120684
Calculating the number of possible paths through some squares
83872
Isomorphisms for graphs with loops and multiple edges