Number of permutations sigma of [2n] without fixed points such that sigma^4 = Id.

A052503

Number of permutations sigma of [2n] without fixed points such that sigma^4 = Id.

Terms

    a(0) =1a(1) =1a(2) =9a(3) =105a(4) =2625a(5) =76545a(6) =3440745a(7) =176080905a(8) =12034447425a(9) =922995698625

External references