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A308671
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a(n) = Sum_{d|n} d^(d^2).
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3
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1, 17, 19684, 4294967313, 298023223876953126, 10314424798490535546171968756, 256923577521058878088611477224235621321608, 6277101735386680763835789423207666416102355444468329480209
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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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L.g.f.: -log(Product_{k>=1} (1 - x^k)^(k^(k^2-1))) = Sum_{k>=1} a(k)*x^k/k.
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MATHEMATICA
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a[n_] := DivisorSum[n, #^(#^2) &]; Array[a, 8] (* Amiram Eldar, May 11 2021 *)
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PROG
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(PARI) {a(n) = sumdiv(n, d, d^d^2)}
(PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-x^k)^(k^(k^2-1))))))
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CROSSREFS
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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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