A317286 Number of permutations of [n] with exactly six increasing runs of even length.

2702765, 117248463, 3118257980, 73830310655, 1708350797975, 38581706239634, 861226758827324, 19346584353278646, 439935779491790415, 10146028258663315691, 238129724283103648476, 5701793180421505562215, 139409020095464012520967, 3483089247393778028230622

Offset

12,1

Links

Alois P. Heinz, Table of n, a(n) for n = 12..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, 7)
    end:
a:= n-> coeff(b(n, 0$2), x, 6):
seq(a(n), n=12..30);

Crossrefs

Column k=6 of A097592.

Sequence in context: A251457 A178291 A212231 * A081409 A251997 A104848

Adjacent sequences: A317283 A317284 A317285 * A317287 A317288 A317289

Keyword

nonn

Author

Alois P. Heinz, Jul 25 2018

Status

approved