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A247951
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a(n) = Product_{i=1..n} sigma_2(i).
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3
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1, 5, 50, 1050, 27300, 1365000, 68250000, 5801250000, 527913750000, 68628787500000, 8372712075000000, 1758269535750000000, 298905821077500000000, 74726455269375000000000, 19428878370037500000000000, 6625247524182787500000000000
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OFFSET
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1,2
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COMMENTS
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a(n) is the product of the sum of the squared divisors of i, for i from 1 to n.
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LINKS
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FORMULA
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a(n) = Product_{i=1..n} A001157(i).
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MAPLE
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with(numtheory): A247951:=n->mul(sigma[2](i), i=1..n): seq(A247951(n), n=1..20);
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MATHEMATICA
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Table[Product[DivisorSigma[2, i], {i, n}], {n, 20}]
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PROG
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(PARI) lista(nn) = vector(nn, n, prod(i=1, n, sigma(i, 2))) \\ Michel Marcus, Oct 01 2014
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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