Number of self-inverse permutations p on [n] with displacement of elements restricted by 3: |p(i)-i| <= 3.

A239075

Number of self-inverse permutations p on [n] with displacement of elements restricted by 3: |p(i)-i| <= 3.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =22a(6) =48a(7) =103a(8) =225a(9) =492a(10) =1076a(11) =2348a(12) =5124a(13) =11184a(14) =24417a(15) =53305a(16) =116366a(17) =254024a(18) =554534a(19) =1210554a(20) =2642656a(21) =5768943a(22) =12593649a(23) =27492040a(24) =60015368a(25) =131014088a(26) =286004920a(27) =624351264a(28) =1362964321a(29) =2975363169

External references