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A277353
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a(n) = Product_{k=1..n} (3*k^2+1).
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2
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1, 4, 52, 1456, 71344, 5422144, 591013696, 87470027008, 16881715212544, 4119138511860736, 1239860692070081536, 451309291913509679104, 195416923398549691052032, 99271797086463243054432256, 58471088483926850159060598784, 39526455815134550707524964777984
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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) ~ 2*3^(n+1/2) * n^(2*n+1) * sinh(Pi/sqrt(3)) / exp(2*n).
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MATHEMATICA
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Table[Product[3*k^2+1, {k, 1, n}], {n, 0, 15}]
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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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