OFFSET
1,2
FORMULA
G.f.: Sum_{k>=1} sigma(k) * x^k/(1 - x^k - x^(2*k)). - Ilya Gutkovskiy, Jul 23 2019
a(n) ~ ((1+sqrt(5))/2)^n / sqrt(5). - Vaclav Kotesovec, Sep 11 2019
MATHEMATICA
Table[Sum[DivisorSigma[1, n/d]*Fibonacci[d], {d, Divisors[n]}], {n, 1, 40}] (* Vaclav Kotesovec, Sep 10 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved