A317287 Number of permutations of [n] with exactly seven increasing runs of even length.

199360981, 11190963430, 378291607803, 11014069796526, 305943708449074, 8211684416287224, 215906484804391566, 5654455021954104792, 148657867362265421769, 3937297418900898841450, 105451222548147683308147, 2864250745636538809593802, 79027581972356621300952774

Offset: 14

Author

Alois P. Heinz, Jul 25 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 14..469

Crossrefs

Column k=7 of A097592.

Programs

Maple

b:= proc(u, o, t) option remember; series(`if`(u+o=0, x^t,
      add(b(u+j-1, o-j, irem(t+1, 2)), j=1..o)+
      add(b(u-j, o+j-1, 0)*x^t, j=1..u)), x, 8)
    end:
a:= n-> coeff(b(n, 0$2), x, 7):
seq(a(n), n=14..30);