%I #16 Oct 28 2022 07:14:19
%S 0,2,6,10,15,32,28,42,60,77,66,136,91,142,201,170,153,302,190,325,370,
%T 332,276,552,390,457,546,598,435,1007,496,682,864,767,883,1270,703,
%U 952,1189,1317,861,1852,946,1396,1875,1382,1128,2216,1400,1952,1995,1921
%N a(n) = (sigma(2n^2)-3)/6.
%C See A065764, A065765 and A097022.
%H Harvey P. Dale, <a href="/A097022/b097022.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = (A065765(n)-3)/6 = A000203(A001105(n) - 3)/6.
%F Sum_{k=1..n} a(k) ~ c * n^3, where c = 4*zeta(3)/Pi^2 = 0.243587... . - _Amiram Eldar_, Oct 28 2022
%t Table[(DivisorSigma[1,2n^2]-3)/6,{n,60}] (* _Harvey P. Dale_, Sep 12 2022 *)
%o (PARI) a(n) = (sigma(2*n^2) - 3)/6; \\ _Michel Marcus_, Dec 20 2013
%Y Cf. A065764, A065765, A000203, A001105, A002117, A072682, A074627, A074628, A074629, A074630, A067051.
%K nonn
%O 1,2
%A _Labos Elemer_, Aug 24 2004