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 - x^k).
MATHEMATICA
a[n_] := DivisorSum[n, DivisorSigma[#, #]^# &]; Array[a, 8] (* Amiram Eldar, Aug 27 2023 *)
PROG
(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)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 14 2022
STATUS
approved