A359052 a(n) = Sum_{d|n} sigma_d(d)^n.

1, 26, 21953, 5554572467, 298500366308609377, 11413459460309090641106905930, 256925761343390078522337875137209684721665, 6476754651706496208416137876625690606583079440495100502628

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..26

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

Cf. A344060, A359053, A359054.

Sequence in context: A015035 A336248 A359054 * A209961 A302396 A208186

Adjacent sequences: A359049 A359050 A359051 * A359053 A359054 A359055

Keyword

nonn

Author

Seiichi Manyama, Dec 14 2022

Status

approved