A321116 Number of permutations p of [n] such that in 0p the largest up-jump equals nine xx and no down-jump is larger than 2.

672, 5454, 40272, 283688, 1948408, 13188482, 88469166, 589852620, 3914957358, 25886899652, 170722453774, 1123938295984, 7390061858416, 48546948619410, 318711158282218, 2091405520367970, 13719823343200698, 89986405527666712, 590148303249975384

Offset: 9

Author

Alois P. Heinz, Oct 27 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 9..1000

Crossrefs

Column k=9 of A291680.

Programs

Maple

b:= proc(u, o, k) option remember; `if`(u+o=0, 1,
      add(b(u-j, o+j-1, k), j=1..min(2, u))+
      add(b(u+j-1, o-j, k), j=1..min(k, o)))
    end:
a:= n-> (k-> b(0, n, k)-b(0, n, k-1))(9):
seq(a(n), n=9..30);