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A360731
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Expansion of Sum_{k>=0} (k * x * (1 + k*x^3))^k.
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5
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1, 1, 4, 27, 257, 3141, 46899, 827639, 16855357, 389100834, 10040378183, 286386193685, 8947506702834, 303875954083536, 11146559606379269, 439178938765108083, 18497974976610341624, 829420114454360154295, 39445018962975879216867
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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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a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^(n-2*k) * binomial(n-3*k,k).
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PROG
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(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x*(1+k*x^3))^k))
(PARI) a(n) = sum(k=0, n\4, (n-3*k)^(n-2*k)*binomial(n-3*k, k));
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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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