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A245503 Number of endofunctions f on [n] such that f^7(i) = f(i) for all i in [n].

%I A245503 #5 Jul 25 2014 09:16:17
%S A245503 1,1,4,21,142,1131,10422,112015,1396516,19702665,306547426,5177584809,
%T A245503 94168757916,1833590759131,38009888806450,835064706091431,
%U A245503 19389119390412448,475039405292487825,12263445905182200882,332913448508180564521,9478703390668813103836
%N A245503 Number of endofunctions f on [n] such that f^7(i) = f(i) for all i in [n].
%H A245503 Alois P. Heinz, <a href="/A245503/b245503.txt">Table of n, a(n) for n = 0..200</a>
%F A245503 E.g.f.: exp(x*exp(x)+x^2*exp(x)^2/2+x^3*exp(x)^3/3+x^6*exp(x)^6/6).
%p A245503 egf:= exp(x*exp(x)+x^2*exp(x)^2/2+x^3*exp(x)^3/3+x^6*exp(x)^6/6):
%p A245503 a:= n-> n!*coeff(series(egf, x, n+1), x, n):
%p A245503 seq(a(n), n=0..25);
%Y A245503 Column k=7 of A245501.
%K A245503 nonn
%O A245503 0,3
%A A245503 _Alois P. Heinz_, Jul 24 2014