The number of bijections $f$ of $\{1, 2,..., n\}$ such that $f(i) \ne i$ for any $i$
9411
Number of permutations of $n$ elements where no number $i$ is in position $i$
133699
Proving that there is a bijection between $A$ and $B$.
101751
The number of words that can be made by permuting the letters of _MATHEMATICS_ is
146990
How to find the number of automorphisms on $\mathbb Z_2\times \mathbb Z_4$
28692
Find if set $I$ of all injective functions $\mathbb{N} \rightarrow \mathbb{N}$ is equinumerous to $\mathbb{R}$
41008
how many permutations of {1,2,...,9}
130381
bijection from $(a,b)$ to $\Bbb R$
57269
A special bijection between $\mathbb{R}\times \mathbb{R}$ and $\mathbb{R}$
73850
Cardinality of set of functions
49833
Simple bijection $\mathbb N_0 \times \mathbb N_0 \to \mathbb N_0$
20199
Find a surjective function $f:\mathbb{N}\to \mathbb{Q}$
82655
Number of Injective Maps
115973
Computing the number of nonisomorphic finite abelian groups of order $n$
18343
Counting homomorphisms between $\Bbb Z$ and $\Bbb Z_n$ and also between $\Bbb Z_n$ and $\Bbb Q$
82675
What is an example of function $f: \Bbb{N} \to \Bbb{Z}$ that is a bijection?
103625
Number of increasing functions from $\{1,2,\dots, n\}$ to itself.
26343
Number of certain (0,1)-matrices, Stanley's Enumerative Combinatorics