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A357147
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a(n) = n! * Sum_{k=0..floor(n/3)} (n - 3*k)^(3*k)/(n - 3*k)!.
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2
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1, 1, 1, 1, 25, 481, 3241, 18481, 1332241, 44198785, 623190961, 15416707681, 1602405014761, 68167258954081, 1598025440555545, 134130467333575441, 14793638741719612321, 730659540435131811841, 34674365632872552887521, 5776415685538277157146305
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OFFSET
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0,5
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LINKS
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FORMULA
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E.g.f.: Sum_{k>=0} x^k / (k! * (1 - (k*x)^3)).
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PROG
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(PARI) a(n) = n!*sum(k=0, n\3, (n-3*k)^(3*k)/(n-3*k)!);
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, x^k/(k!*(1-(k*x)^3)))))
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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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