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A360730
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Expansion of Sum_{k>=0} (k * x * (1 + k*x^2))^k.
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5
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1, 1, 4, 28, 272, 3368, 50768, 902397, 18481408, 428556075, 11099001600, 317544062217, 9946366838784, 338537433281448, 12441407233436672, 491002325860132371, 20710640842719301632, 929821866165431838038, 44270378887441746923520
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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/3)} (n-2*k)^(n-k) * binomial(n-2*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^2))^k))
(PARI) a(n) = sum(k=0, n\3, (n-2*k)^(n-k)*binomial(n-2*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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