%I #20 Jul 21 2018 02:58:20
%S 1,-2,2,-4,6,-6,6,-6,6,-4,0,2,-2,6,-10,6,-2,2,2,-10,16,-18,18,-22,26,
%T -18,10,-12,4,10,-14,18,-22,24,-26,18,-8,6,6,-24,28,-34,44,-38,30,-28,
%U 14,2,-10,22,-28,36,-50,38,-30,44,-28,0,2,-10,34,-54,66,-66,70,-82,60
%N Expansion of Product_{k>=1} (1 - x^(k*(k+1)/2)) / (1 + x^(k*(k+1)/2)).
%C For n <= 10^4, a(n) = 0 for n = 10, 57, 78, 136, 141.
%H Seiichi Manyama, <a href="/A316788/b316788.txt">Table of n, a(n) for n = 0..10000</a>
%F Convolution inverse of A280366.
%p seq(coeff(series(mul((1-x^(k*(k+1)/2))/(1+x^(k*(k+1)/2)),k=1..n), x,n+1),x,n),n=0..70); # _Muniru A Asiru_, Jul 14 2018
%t nmax = 100; CoefficientList[Series[Product[(1 - x^(k*(k+1)/2)) / (1 + x^(k*(k+1)/2)), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Jul 14 2018 *)
%Y Cf. A280366, A292518, A292519.
%K sign
%O 0,2
%A _Seiichi Manyama_, Jul 13 2018