OFFSET
1,2
FORMULA
a(n) ~ 3^(n-1). - Vaclav Kotesovec, Sep 11 2019
a(n) = Sum_{d|n} sigma(n/d)*3^(d-1). - Wesley Ivan Hurt, Dec 31 2023
MATHEMATICA
Table[Sum[DivisorSigma[1, n/d]*3^(d - 1), {d, Divisors[n]}], {n, 1, 25}] (* Vaclav Kotesovec, Sep 10 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved