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

Author

Alois P. Heinz, Jul 25 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 12..470

Crossrefs

Column k=6 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, 7)
    end:
a:= n-> coeff(b(n, 0$2), x, 6):
seq(a(n), n=12..30);