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A371775
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a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-k+1,n-3*k).
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3
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1, 5, 36, 287, 2396, 20539, 179125, 1581282, 14085997, 126357958, 1139825257, 10328791996, 93951594230, 857328996139, 7844767641718, 71951952863375, 661311093597592, 6089245462608316, 56160004711457917, 518707264791838694, 4797177987838607105
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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) = [x^n] 1/(((1-x)^2-x^3) * (1-x)^(3*n)).
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PROG
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(PARI) a(n) = sum(k=0, n\3, binomial(4*n-k+1, n-3*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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