A321116 - OEIS

%I #5 Oct 27 2018 16:24:56

%S 672,5454,40272,283688,1948408,13188482,88469166,589852620,3914957358,

%T 25886899652,170722453774,1123938295984,7390061858416,48546948619410,

%U 318711158282218,2091405520367970,13719823343200698,89986405527666712,590148303249975384

%N 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.

%H Alois P. Heinz, <a href="/A321116/b321116.txt">Table of n, a(n) for n = 9..1000</a>

%p b:= proc(u, o, k) option remember; `if`(u+o=0, 1,

%p       add(b(u-j, o+j-1, k), j=1..min(2, u))+

%p       add(b(u+j-1, o-j, k), j=1..min(k, o)))

%p     end:

%p a:= n-> (k-> b(0, n, k)-b(0, n, k-1))(9):

%p seq(a(n), n=9..30);

%Y Column k=9 of A291680.

%K nonn

%O 9,1

%A _Alois P. Heinz_, Oct 27 2018