OFFSET
1,2
LINKS
Vaclav Kotesovec, Graph - the asymptotic ratio (100000 terms)
FORMULA
Conjecture: a(n) ~ A372675(n) / 2 ~ Pi^4 * n^4 / (288*zeta(3)). - Vaclav Kotesovec, May 13 2024
MATHEMATICA
Table[Sum[DivisorSigma[1, k*n], {k, 1, n}], {n, 1, 50}] (* Vaclav Kotesovec, May 13 2024 *)
PROG
(PARI) a(n) = sum(k=1, n, sigma(n*k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 11 2024
STATUS
approved