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A359054
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a(n) = Sum_{d|n} sigma_d(d)^d.
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3
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1, 26, 21953, 5554571867, 298500366308609377, 11413459460309090640625021978, 256925761343390078522337875137209684721665, 6476754651706496208416137876625690606552226172163824554588
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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} (sigma_k(k) * x)^k/(1 - x^k).
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MATHEMATICA
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a[n_] := DivisorSum[n, DivisorSigma[#, #]^# &]; Array[a, 8] (* Amiram Eldar, Aug 27 2023 *)
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PROG
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(PARI) a(n) = sumdiv(n, d, sigma(d, d)^d);
(PARI) my(N=10, x='x+O('x^N)); Vec(sum(k=1, N, (sigma(k, k)*x)^k/(1-x^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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