A245505 Number of endofunctions f on [n] such that f^9(i) = f(i) for all i in [n].

1, 1, 4, 19, 116, 901, 8422, 89755, 1066088, 14154409, 212952266, 3646226959, 69912304156, 1460516349709, 32480282189006, 759186766079011, 18569220500830928, 475114325555073745, 12719547174925542034, 356098625214192355735, 10413932958067814029316

Offset: 0

Author

Alois P. Heinz, Jul 24 2014

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..200

Crossrefs

Column k=9 of A245501.

Programs

Maple

egf:= exp(add((x*exp(x))^(2^j)/(2^j), j=0..3)):
a:= n-> n!*coeff(series(egf, x, n+1), x, n):
seq(a(n), n=0..25);

Formula

E.g.f.: exp(Sum_{j=0..3} (x*exp(x))^(2^j)/(2^j)).