OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..2094
FORMULA
a(n) ~ 3^(n-1). - Vaclav Kotesovec, Sep 11 2019
G.f.: Sum_{k>=1} 3^(k-1)*x^k / (1 - 2*x^k). - Ilya Gutkovskiy, Sep 22 2020
MAPLE
f:= n -> add(2^d * 3^(n/d)/6, d = numtheory:-divisors(n)):
map(f, [$1..50]); # Robert Israel, Jun 25 2020
MATHEMATICA
Table[Sum[2^(d - 1)*3^(n/d - 1), {d, Divisors[n]}], {n, 1, 30}] (* Vaclav Kotesovec, Sep 11 2019 *)
PROG
(PARI) a(n) = sumdiv(n, d, 2^(d-1) * 3^(n/d-1) ); /* Joerg Arndt, Apr 14 2013 */
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved