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A097022
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a(n) = (sigma(2n^2)-3)/6.
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3
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0, 2, 6, 10, 15, 32, 28, 42, 60, 77, 66, 136, 91, 142, 201, 170, 153, 302, 190, 325, 370, 332, 276, 552, 390, 457, 546, 598, 435, 1007, 496, 682, 864, 767, 883, 1270, 703, 952, 1189, 1317, 861, 1852, 946, 1396, 1875, 1382, 1128, 2216, 1400, 1952, 1995, 1921
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Sum_{k=1..n} a(k) ~ c * n^3, where c = 4*zeta(3)/Pi^2 = 0.243587... . - Amiram Eldar, Oct 28 2022
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MATHEMATICA
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Table[(DivisorSigma[1, 2n^2]-3)/6, {n, 60}] (* Harvey P. Dale, Sep 12 2022 *)
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PROG
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(PARI) a(n) = (sigma(2*n^2) - 3)/6; \\ Michel Marcus, Dec 20 2013
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CROSSREFS
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Cf. A065764, A065765, A000203, A001105, A002117, A072682, A074627, A074628, A074629, A074630, A067051.
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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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