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A132303
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Sum of cubes of trinomial coefficients: a(n) = Sum_{k=0..2n} trinomial(n,k)^3 where trinomial(n,k) = [x^k] (1 + x + x^2)^n.
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4
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1, 3, 45, 831, 17181, 375903, 8530929, 198643455, 4714491357, 113550338127, 2767105469745, 68077260387315, 1688160321677025, 42142679453321307, 1058050429855640217, 26695057057648257231, 676431705046728704733
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OFFSET
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0,2
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LINKS
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PROG
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(PARI) a(n)=sum(k=0, 2*n, polcoeff((1+x+x^2)^n, k)^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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