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A321564
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a(n) = Sum_{d divides n} (-1)^(d + n/d) * d^8.
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4
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1, -257, 6562, -65281, 390626, -1686434, 5764802, -16711425, 43053283, -100390882, 214358882, -428373922, 815730722, -1481554114, 2563287812, -4278124289, 6975757442, -11064693731, 16983563042, -25500455906, 37828630724, -55090232674
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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^8*x^k/(1 + x^k). - Ilya Gutkovskiy, Dec 22 2018
Multiplicative with a(2^e) = -(127*2^(8*e+1) + 511)/255, and a(p^e) = (p^(8*e+8) - 1)/(p^8 - 1) for p > 2. - Amiram Eldar, Nov 22 2022
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MATHEMATICA
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a[n_] := DivisorSum[n, (-1)^(# + n/#)*#^8 &]; 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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