Number of permutations p of [n] with no fixed points and displacement of elements restricted by four: 1 <= |p(i)-i| <= 4.

A259777

Number of permutations p of [n] with no fixed points and displacement of elements restricted by four: 1 <= |p(i)-i| <= 4.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =9a(5) =44a(6) =168a(7) =536a(8) =1661a(9) =5328a(10) =18129a(11) =62592a(12) =214657a(13) =726614a(14) =2438656a(15) =8192120a(16) =27614544a(17) =93315688a(18) =315490856a(19) =1065719578a(20) =3597204049a(21) =12138879608a(22) =40968868129a(23) =138302514360a(24) =466929286109

External references