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A371778
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a(n) = Sum_{k=0..floor(n/3)} binomial(3*n+2,n-3*k).
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3
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1, 5, 28, 166, 1015, 6324, 39901, 254035, 1628380, 10493680, 67914088, 441086947, 2873255906, 18763759019, 122803467241, 805241108334, 5288922607095, 34789875710568, 229147231044397, 1511104857207706, 9975701630282920, 65920216186587257
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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)^3-x^3) * (1-x)^(2*n)).
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PROG
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(PARI) a(n) = sum(k=0, n\3, binomial(3*n+2, 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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