Combinatorics.Permutation.WithoutSomeFixpoints

Documentation

enumerate :: Eq a => Int -> [a] -> [[a]]

enumerate n xs list all permutations of xs where the first n elements do not keep their position (i.e. are no fixpoints).

This is a generalization of derangement.

Naive but comprehensible implementation.

numbers :: Num a => [[a]]

http://oeis.org/A047920