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

9,1

Links

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

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);

Crossrefs

Column k=9 of A291680.

Sequence in context: A231740 A245778 A245786 * A234481 A234476 A340864

Adjacent sequences: A321113 A321114 A321115 * A321117 A321118 A321119

Keyword

nonn

Author

Alois P. Heinz, Oct 27 2018

Status

approved