A359053 a(n) = Sum_{d|n} sigma_d(d)^(n/d).
1, 6, 29, 299, 3127, 48360, 823545, 16918164, 387462126, 10019541652, 285311670613, 8920567022545, 302875106592255, 11113363273445312, 437893951476881153, 18447309245488431653, 827240261886336764179, 39346708488214110663954, 1978419655660313589123981
Offset: 1
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 1..386
Programs
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Mathematica
a[n_] := DivisorSum[n, DivisorSigma[#, #]^(n/#) &]; Array[a, 19] (* Amiram Eldar, Aug 27 2023 *)
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PARI
a(n) = sumdiv(n, d, sigma(d, d)^(n/d));
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PARI
my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, sigma(k, k)*x^k/(1-sigma(k, k)*x^k)))
Formula
G.f.: Sum_{k >= 1} sigma_k(k) * x^k/(1 - sigma_k(k) * x^k).
If p is prime, a(p) = 2 + p^p.