Number of total orders on set with $n$ elements
116251
Number of distinct total orders on a set
122959
How is number of conjugacy class related to the order of a group?
111324
Finding number of relations on a set with 3 elements
150156
Proving that $S_n$ has order $n!$
147484
For a set with N members, what is the number of set partitions in which each subset is either of size 1 or 2?
6432
How many ways can N elements be partitioned into subsets of size K?
6679
Counting number of subsets which contain a specific element
108957
Cardinality of a totally ordered union
47592
Integer partitions in all orderings
82207
Number of Pairs of Subsets
81505
Derangement of $n$ elements
97314
Counting nearly-sorted permutations
137621
The Number of Topologies on a Finite Set
48502
number of ordered pairs of integers $(x,y)$ satisfying the equation
11967
number of subsets of even and odd
9651
Cardinality of cartesian product of an infinite set with N
55840
Number of functions from n-element set to {1, 2, …, m}