A317290 Number of permutations of [n] with exactly ten increasing runs of even length.

370371188237525, 38563334673062963, 2325983895636537462, 113126812608590106065, 4980791141860424686096, 206198935127851667065607, 8187758750644879282198684, 316873661623427502461383547, 12080329061828597152861716278, 456708256439969037699279918515

Offset: 20

Author

Alois P. Heinz, Jul 25 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 20..468

Crossrefs

Column k=10 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, 11)
    end:
a:= n-> coeff(b(n, 0$2), x, 10):
seq(a(n), n=20..30);