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A308675
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a(n) = Sum_{d|n} d^(d^2 * n).
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2
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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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L.g.f.: -log(Product_{k>=1} (1 - (k^(k^2)*x)^k)^(1/k)) = Sum_{k>=1} a(k)*x^k/k.
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MATHEMATICA
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Table[Total[#^(#^2 n)&/@Divisors[n]], {n, 5}] (* Harvey P. Dale, Feb 29 2020 *)
a[n_] := DivisorSum[n, #^(n * #^2) &]; Array[a, 5] (* Amiram Eldar, May 11 2021 *)
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PROG
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(PARI) {a(n) = sumdiv(n, d, d^(d^2*n))}
(PARI) N=10; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-(k^k^2*x)^k)^(1/k)))))
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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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