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A293286
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a(n) = A181544(2n, 2n-1).
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0
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20, 8464, 4050864, 2116980800, 1173644492800, 678353946298560, 404352269157205152, 246796318508780847360, 153477802845690943118400, 96903346351876187722368000, 61954834924471706682462940800, 40029904663914104968204952365824, 26096917229103772343967114415006304
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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t[n_, k_] := SeriesCoefficient[Sum[Binomial[n + j, j]^3 x^j, {j, 0, n + k}] (1 - x)^(3n + 1), {x, 0, k}];
a[n_] := t[2n, 2n - 1];
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PROG
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(Sage)
def a(n) :
R.<x> = QQ[]; p = 2*n; q = 2*n-1
return ((1-x)^(3*p+1) * sum(binomial(p+r, r)^3 * x^r for r in [0..p+q]))[q]
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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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