%I #8 Apr 03 2019 02:56:13
%S 1,1,1,1,2,2,4,4,8,9,17,19,38,42,80,97,174,208,389,460,826,1049,1790,
%T 2248,3989,4933,8451,11116,18300,23742,40446,51774,85774,115454,
%U 184806,245967,406768,533210,860295,1179570,1850325,2505585,4046594,5407269,8556317,11877833,18327723
%N Expansion of Sum_{k>=0} x^(k^2) / Product_{j=1..k} (1 - j*x^j).
%p a:=series(add(x^(k^2)/mul((1-j*x^j),j=1..k),k=0..100),x=0,47): seq(coeff(a,x,n),n=0..46); # _Paolo P. Lava_, Apr 02 2019
%t nmax = 46; CoefficientList[Series[Sum[x^k^2/Product[(1 - j x^j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
%Y Cf. A193196, A204856, A318771.
%K nonn
%O 0,5
%A _Ilya Gutkovskiy_, Sep 03 2018