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A091986
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a(0)=1, a(n) = sigma_3(2n).
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4
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1, 9, 73, 252, 585, 1134, 2044, 3096, 4681, 6813, 9198, 11988, 16380, 19782, 25112, 31752, 37449, 44226, 55261, 61740, 73710, 86688, 97236, 109512, 131068, 141759, 160454, 183960, 201240, 219510, 257544, 268128, 299593, 335664, 358722, 390096, 442845
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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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Sum_{k=1..n} a(k) ~ (17*zeta(4)/8) * n^4. - Amiram Eldar, Dec 12 2023
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MATHEMATICA
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Join[{1}, Table[DivisorSigma[3, n], {n, 2, 80, 2}]] (* Harvey P. Dale, Feb 26 2011 *)
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PROG
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(PARI) a(n) = if(n < 1, 1, sigma(2*n, 3)); \\ Amiram Eldar, Dec 12 2023
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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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