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A062785
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a(n) = Chowla's function of n * sigma(n).
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1
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0, 0, 0, 14, 0, 60, 0, 90, 39, 126, 0, 420, 0, 216, 192, 434, 0, 780, 0, 882, 320, 468, 0, 2100, 155, 630, 480, 1512, 0, 2952, 0, 1890, 672, 1026, 576, 4914, 0, 1260, 896, 4410, 0, 5088, 0, 3276, 2496, 1800, 0, 9300, 399, 3906, 1440, 4410, 0, 7800, 1152, 7560, 1760, 2790, 0, 17976, 0, 3168, 4160, 7874, 1512
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OFFSET
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1,4
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LINKS
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FORMULA
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Sum_{k=1..n} a(k) ~ (5*zeta(3)/6 - Pi^2/18) * n^3. - Amiram Eldar, Apr 01 2024
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MATHEMATICA
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a[n_] := Module[{s = DivisorSigma[1, n]}, s*(s - n - 1)]; a[1] = 0; Array[a, 100] (* Amiram Eldar, Apr 01 2024 *)
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PROG
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(PARI) a(n) = {my(s = sigma(n)); if(n == 1, 0, s*(s-n-1)); }
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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