OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..386
FORMULA
a(n) = [x^n] (1/(1-x)) * Sum_{k>=1} sigma_n(k) * x^k/(1 - x^k).
a(n) = Sum_{k=1..n} Sum_{d|k} d^n * tau(k/d).
a(n) = Sum_{k=1..n} Sum_{d|k} sigma_n(d).
a(n) ~ c * n^n, where c = 1/(1 - 1/exp(1)) = A185393. - Vaclav Kotesovec, Aug 07 2022
PROG
(PARI) a(n) = sum(k=1, n, sigma(k, n)*(n\k));
(PARI) a(n) = sum(k=1, n, sumdiv(k, d, d^n*numdiv(k/d)));
(PARI) a(n) = sum(k=1, n, sumdiv(k, d, sigma(d, n)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 24 2022
STATUS
approved