OFFSET
1,2
FORMULA
a(n) ~ 2 * 3^(n-1). - Vaclav Kotesovec, Sep 11 2019
G.f.: Sum_{k>=1} 3^(k-1)*x^k / (1 - 3*x^k). - Ilya Gutkovskiy, Sep 22 2020
MATHEMATICA
Table[Sum[3^(d + n/d - 2), {d, Divisors[n]}], {n, 1, 30}] (* Vaclav Kotesovec, Sep 10 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved