OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: Sum_{k>=1} k*(k^2 - 1)*x^k/(1 - x^k). - Ilya Gutkovskiy, Mar 17 2017
G.f.: 6 * Sum_{k>0} x^(2*k)/(1-x^k)^4. - Seiichi Manyama, Jun 11 2023
PROG
(PARI) a(n) = sigma(n, 3)-sigma(n); \\ Seiichi Manyama, Jun 11 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 20 2004
STATUS
approved