OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = Sum_{d|n} d*(3*d-1)/2.
G.f.: Sum_{k>=1} k*(3*k-1)/2*x^k/(1 - x^k). - Ilya Gutkovskiy, May 23 2017
MATHEMATICA
Table[Sum[d*(3d - 1)/2, {d, Divisors[n]}], {n, 101}] (* Indranil Ghosh, May 23 2017 *)
PROG
(PARI) a(n) = sumdiv(n, d, d*(3*d-1)/2); \\ Michel Marcus, Mar 25 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Mar 19 2006
EXTENSIONS
More terms from Michel Marcus, Mar 25 2015
STATUS
approved