OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
Sum_{k=1..n} a(k) ~ c * n^3, where c = 4*zeta(3)/Pi^2 = 0.243587... . - Amiram Eldar, Oct 28 2022
MATHEMATICA
Table[(DivisorSigma[1, 2n^2]-3)/6, {n, 60}] (* Harvey P. Dale, Sep 12 2022 *)
PROG
(PARI) a(n) = (sigma(2*n^2) - 3)/6; \\ Michel Marcus, Dec 20 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Aug 24 2004
STATUS
approved