OFFSET
1,2
FORMULA
a(n) ~ 2^(n-1). - Vaclav Kotesovec, Sep 11 2019
MATHEMATICA
Table[Sum[DivisorSigma[1, n/d]*2^(d - 1), {d, Divisors[n]}], {n, 1, 40}] (* Vaclav Kotesovec, Sep 10 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved