Finding the number of surjective distributions
61
Calculating the total number of surjective functions
141225
Number of all bijective functions from A to A.
26569
Counting binary operations on a set with $n$ elements
12803
Proof for number of weak compositions
115973
Computing the number of nonisomorphic finite abelian groups of order $n$
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?
74453
Injective and Surjective Functions
41359
Constructing a bijection
117862
Number of partitions of an $n$-element set into $k$ classes
65574
How to prove that total number of non-isomorphic labelled trees of order $n$ is $n^{n-2}$?
79974
The cardinality of Lebesgue sets
114752
Number of permutations of a specific cycle decomposition
9411
Number of permutations of $n$ elements where no number $i$ is in position $i$
67451
Building a bijection from a finite union of countable sets to $\mathbb{N}$
55840
Number of functions from n-element set to {1, 2, …, m}
113109
Showing that a map is bijective and finding its inverse
117793
Finding a function $\mathbb{N} \to \mathbb{N}$ that is surjective but not injective.