OFFSET
1,2
FORMULA
a(n) ~ 2^(2*n-2) / (sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Sep 11 2019
MATHEMATICA
Table[Sum[CatalanNumber[n/d - 1]*DivisorSigma[0, d], {d, Divisors[n]}], {n, 1, 25}] (* Vaclav Kotesovec, Sep 10 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved