A245915 Number of pairs of endofunctions f, g on [n] satisfying f(g^6(i)) = f(i) for all i in [n].

1, 1, 12, 297, 11104, 578745, 46097856, 4892935369, 649893820416, 108501530261841, 21500188932505600, 4911081373878751401, 1343217062946070130688, 427404076347462876047113, 154711214699181287350984704, 64222714159878924347124911625

Offset: 0

Author

Alois P. Heinz, Aug 06 2014

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..150

Crossrefs

Column k=6 of A245910.

Programs

Maple

with(combinat):
b:= proc(n, i) option remember; unapply(`if`(n=0 or i=1, x^n,
      expand(add((i-1)!^j*multinomial(n, n-i*j, i$j)/j!*
      x^(igcd(i, 6)*j)*b(n-i*j, i-1)(x), j=0..n/i))), x)
    end:
a:= n-> add(binomial(n-1, j-1)*n^(n-j)*b(j$2)(n), j=0..n):
seq(a(n), n=0..20);