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A139468
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a(n) = Sum{k=0..n} C(n,3k+1)^2.
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3
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0, 1, 4, 9, 17, 50, 261, 1275, 5028, 17253, 58601, 218042, 876789, 3537847, 13783018, 52301709, 198627921, 767778786, 3010327497, 11824753551, 46200429186, 179787741723, 700285942731, 2738134757118, 10739885115573, 42164261091351, 165467386466802
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OFFSET
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0,3
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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, 3k+1]^2, {k, 0, n}], {n, 0, 30}] (* Harvey P. Dale, Sep 08 2018 *)
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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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