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A367113
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G.f. satisfies A(x) = 1 + 2*x*A(x) + 2*x^3*A(x)^3.
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4
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1, 2, 4, 10, 32, 112, 396, 1416, 5184, 19424, 73984, 285056, 1108848, 4350816, 17203008, 68473504, 274122752, 1103014912, 4458611968, 18096793088, 73724852224, 301360575488, 1235633545216, 5080554352640, 20943623880448, 86541514460672, 358386391051264
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{k=0..floor(n/3)} 2^(n-2*k) * binomial(n,3*k) * A001764(k).
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PROG
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(PARI) a(n) = sum(k=0, n\3, 2^(n-2*k)*binomial(n, 3*k)*binomial(3*k, k)/(2*k+1));
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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