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A245916 Number of pairs of endofunctions f, g on [n] satisfying f(g^7(i)) = f(i) for all i in [n]. 2
1, 1, 10, 159, 3496, 98345, 3373056, 729481375, 187564765312, 37157158911249, 6404841810150400, 1033733019005497151, 162392131536566261760, 25373998461297751027321, 13879265226159974639036416, 11935104515280353051806269375, 7611603822558997773619173031936 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

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, 7)*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);

CROSSREFS

Column k=7 of A245910.

Sequence in context: A268883 A283721 A239761 * A245914 A239762 A087961

Adjacent sequences:  A245913 A245914 A245915 * A245917 A245918 A245919

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 06 2014

STATUS

approved

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Last modified October 22 16:15 EDT 2021. Contains 348174 sequences. (Running on oeis4.)