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A245503
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Number of endofunctions f on [n] such that f^7(i) = f(i) for all i in [n].
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2
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1, 1, 4, 21, 142, 1131, 10422, 112015, 1396516, 19702665, 306547426, 5177584809, 94168757916, 1833590759131, 38009888806450, 835064706091431, 19389119390412448, 475039405292487825, 12263445905182200882, 332913448508180564521, 9478703390668813103836
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OFFSET
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0,3
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LINKS
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FORMULA
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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).
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MAPLE
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egf:= exp(x*exp(x)+x^2*exp(x)^2/2+x^3*exp(x)^3/3+x^6*exp(x)^6/6):
a:= n-> n!*coeff(series(egf, x, n+1), x, n):
seq(a(n), n=0..25);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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