cp's OEIS Frontend

A245504 Number of endofunctions f on [n] such that f^8(i) = f(i) for all i in [n].

%I A245504 #10 Jun 01 2025 19:54:31
%S A245504 1,1,3,10,41,196,1057,7042,87473,2004328,50881121,1200507694,
%T A245504 26179091017,538344201292,10635924720449,204889902343666,
%U A245504 3902206399428833,74966895289570768,1511315984060460865,34267718094037895638,937490346932078590841,30931366331911427839156
%N A245504 Number of endofunctions f on [n] such that f^8(i) = f(i) for all i in [n].
%H A245504 Alois P. Heinz, <a href="/A245504/b245504.txt">Table of n, a(n) for n = 0..200</a>
%F A245504 E.g.f.: exp(x*exp(x)+x^7*exp(x)^7/7).
%p A245504 egf:= exp(x*exp(x)+x^7*exp(x)^7/7):
%p A245504 a:= n-> n!*coeff(series(egf, x, n+1), x, n):
%p A245504 seq(a(n), n=0..25);
%t A245504 With[{nn=30},CoefficientList[Series[Exp[x Exp[x]+(x^7 Exp[x]^7)/7],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jan 10 2016 *)
%Y A245504 Column k=8 of A245501.
%K A245504 nonn
%O A245504 0,3
%A A245504 _Alois P. Heinz_, Jul 24 2014