OFFSET
1,1
FORMULA
Sum_{k=1..n} a(k) ~ 2*n * (log(n) + 2*gamma - 1 + 2*log(3)) / 3, where gamma is the Euler-Mascheroni constant A001620.
MATHEMATICA
Table[DivisorSigma[0, 3*n-1], {n, 1, 150}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, May 11 2024
STATUS
approved