Number of partitions of an integer, if the partitions are no larger than $2$
4559
How many ways can $133$ be written as sum of only $1s$ and $2s$
26569
Counting binary operations on a set with $n$ elements
72591
Find a bijection to prove a fact about integer partitions
76405
Let n be an even integer. How many different ways can I choose subsets of the set {1,2...,n}
93459
Number of permutations of unspecified length
142038
Finding the number of elements of order two in the symmetric group $S_4$
142477
Closed-form expression for the number of $k$-permutations of length $n$. Duplicates allowed!
47799
Show that the number or $r$ combinations of $X$ which contain no consecutive integers is given by $\binom{n-r+1}{r}$
117658
A set with n elements has 2^n subsets
21754
Partition a set into subsets of size $k$
8446
Number of solutions over positive integers of $x_1 + x_2 + ... + x_n = S$ for $x_i \in [0, 25]$
44013
How many trees over ${1,2,3,...n}$ with conditions
43979
The total number of subsets is $2^n$ for $n$ elements
92941
# of partitions of $n$ into at most $r$ positive integers $=$ # of partitions of $n + r$ into exactly $r$ positive integers?
86902
Consider the smallest number in each of the $n\choose r$ subsets (of size $r$) of $S=\{1,2,\ldots,n\}$...
82872
Combinatorial proof involving partitions and generating functions
28496
Generating the partitions of a number