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A359052
a(n) = Sum_{d|n} sigma_d(d)^n.
3
1, 26, 21953, 5554572467, 298500366308609377, 11413459460309090641106905930, 256925761343390078522337875137209684721665, 6476754651706496208416137876625690606583079440495100502628
OFFSET
1,2
LINKS
FORMULA
G.f.: Sum_{k >= 1} (sigma_k(k) * x)^k/(1 - (sigma_k(k) * x)^k).
MATHEMATICA
a[n_] := DivisorSum[n, DivisorSigma[#, #]^n &]; Array[a, 8] (* Amiram Eldar, Aug 27 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, sigma(d, d)^n);
(PARI) my(N=10, x='x+O('x^N)); Vec(sum(k=1, N, (sigma(k, k)*x)^k/(1-(sigma(k, k)*x)^k)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 14 2022
STATUS
approved