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A321565
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a(n) = Sum_{d divides n} (-1)^(d + n/d) * d^9.
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52
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1, -513, 19684, -261633, 1953126, -10097892, 40353608, -133955073, 387440173, -1001953638, 2357947692, -5149983972, 10604499374, -20701400904, 38445332184, -68584996353, 118587876498, -198756808749, 322687697780, -511002214758
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: Sum_{k>=1} (-1)^(k+1)*k^9*x^k/(1 + x^k). - Ilya Gutkovskiy, Dec 22 2018
Multiplicative with a(2^e) = -3*(85*2^(9*e+1) + 341)/511, and a(p^e) = (p^(9*e+9) - 1)/(p^9 - 1) for p > 2. - Amiram Eldar, Nov 22 2022
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MATHEMATICA
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CoefficientList[Series[Sum[(-1)^(k+1) k^9 x^k/(1+x^k), {k, 20}], {x, 0, 20}], x] (* Harvey P. Dale, Apr 09 2019 *)
a[n_] := DivisorSum[n, (-1)^(# + n/#)*#^9 &]; Array[a, 25] (* Amiram Eldar, Nov 22 2022 *)
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PROG
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CROSSREFS
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KEYWORD
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sign,mult
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AUTHOR
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STATUS
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approved
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