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A368067
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a(n) = Product_{i=1..n, j=1..n} (i^2 + 3*i*j + j^2).
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3
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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) ~ 5^(5*n*(n+1)/2 + 1/2) * n^(2*n^2 - 1) / (2 * Pi * exp(3*n^2) * phi^(sqrt(5)*(n*(n+1) + 1/6) - 1/2)), where phi = A001622 is the golden ratio.
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MATHEMATICA
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Table[Product[i^2 + 3*i*j + j^2, {i, 1, n}, {j, 1, n}], {n, 0, 7}]
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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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