Number of self-inverse permutations p on [n] with displacement of elements restricted by 9: |p(i)-i| <= 9.

A239081

Number of self-inverse permutations p on [n] with displacement of elements restricted by 9: |p(i)-i| <= 9.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =26a(6) =76a(7) =232a(8) =764a(9) =2620a(10) =9496a(11) =33076a(12) =112428a(13) =372436a(14) =1214976a(15) =3913582a(16) =12529522a(17) =39989374a(18) =127728664a(19) =409169795a(20) =1317486613a(21) =4256424244a(22) =13780938480a(23) =44667060684a(24) =144831314468a(25) =469535390016

External references