Fixed-point-free permutations
9411
Number of permutations of $n$ elements where no number $i$ is in position $i$
69827
Set conditions at a permutation
41726
Musical and combinatorial proof
8645
A formula for bit strings with no $k$ consecutive $1$'s using generating functions
60416
Finding a permutation, and number of, from powers of the permutation
86389
Combinatorial argument to prove the recurrence relation for number of derangements
17268
Cycles in permutations of a given size
29678
Circular Permutation
133497
Group Membership Test for Permutations
75227
If $S=\{1,2,\dots,n\}$ and $P_n(k)$ be the number of permutations of $S$ having $k$ fixed points, then $\sum_{k=0}^nk.P_{n}(k)=n!$
84317
Iterated self-composition of arbitrary function
61324
Finding the "square root" of a permutation
75223
Generate all possible permutations (or n-tuples)
73323
Permutations when some objects are alike
105452
permutation in c#
148703
Permutations with repeating digits
2396
Order-preserving injections of ordinals into $[0,1]$