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A367943
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a(n) = Product_{i=1..n, j=1..n} (i^2 + 4*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) ~ c * n^(2*n^2 - 1/2) * 5^(n*(n+1)) * 2^(-n) * exp(n*(n+1)*(2*Pi - 3*arctan(2))/2 - 3*n^2) , where c = 0.4523180383519335764034720087114905921141637339852374451758854101884791581...
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MATHEMATICA
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Table[Product[i^2+4*j^2, {i, 1, n}, {j, 1, n}], {n, 0, 8}]
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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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