A317285 Number of permutations of [n] with exactly five increasing runs of even length.

50521, 1629248, 32918922, 617859020, 11668739836, 217316513198, 4043244094251, 76688877688570, 1487035437929625, 29470163960950720, 598896893196470516, 12504145259394103084, 268208623687371202156, 5911352523792061709194, 133914475861667199021171

Offset

10,1

Links

Alois P. Heinz, Table of n, a(n) for n = 10..470

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, 6)
    end:
a:= n-> coeff(b(n, 0$2), x, 5):
seq(a(n), n=10..30);

Crossrefs

Column k=5 of A097592.

Sequence in context: A231918 A029823 A302902 * A253032 A251486 A376929

Adjacent sequences: A317282 A317283 A317284 * A317286 A317287 A317288

Keyword

nonn

Author

Alois P. Heinz, Jul 25 2018

Status

approved