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A139469
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a(n) = Sum_{k=0..n} C(n,3k+2)^2.
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4
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0, 0, 1, 9, 36, 101, 261, 882, 3921, 17253, 67554, 243695, 876789, 3324906, 13166791, 52301709, 203824548, 782913717, 3010327497, 11695756698, 45823049817, 179787741723, 703527078258, 2747647985241, 10739885115573, 42082084255050, 165225573240651
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OFFSET
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0,4
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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Table[Sum[Binomial[n, 3*k + 2]^2, {k, 0, n}], {n, 0, 40}] (* Vaclav Kotesovec, Mar 12 2019 *)
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PROG
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(PARI) a(n) = sum(k=0, n, binomial(n, 3*k+2)^2); \\ Michel Marcus, Mar 12 2019
(Magma) [&+[Binomial(n, 3*k+2)^2: k in [0..n]]: n in [0..30]]; // Vincenzo Librandi, Mar 14 2019
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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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