%I #16 Jun 24 2018 11:34:00
%S 1,3,5,-2,-6,-35,-4,8,16,-62,-158,-1149,56,556,680,-1566,-4966,3544,
%T 6132,20268,15792,-75194,-162814,-1246153,333904,805112,235968,
%U -2775034,-5259270,7160120,15199212,25457976,-4403208,-119142438,-161039518,211525304,635914664
%N Product_{k>=1} 1/(1 - a(k)*x^k) = 1 + Sum_{k>=1} k^2*x^k.
%H Seiichi Manyama, <a href="/A316086/b316086.txt">Table of n, a(n) for n = 1..500</a>
%e 1/((1-x)*(1-3*x^2)*(1-5*x^3)*(1+2*x^4)* ... ) = 1 + x + 4*x^2 + 9*x^3 + 16*x^4 + ... .
%Y Cf. A147559, A253909, A316087.
%K sign
%O 1,2
%A _Seiichi Manyama_, Jun 24 2018