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A372710
a(n) = Sum_{k=1..n} sigma(n*k),
2
1, 10, 29, 81, 121, 302, 321, 630, 801, 1264, 1177, 2521, 1961, 3234, 4013, 5140, 4267, 8013, 5921, 10701, 10685, 12166, 10321, 20458, 15552, 19610, 21469, 28473, 20671, 40340, 25377, 40351, 39557, 43048, 45849, 70020, 43131, 59690, 63813, 89154, 58087, 106310
OFFSET
1,2
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