%I #10 Jun 16 2018 12:16:55
%S 1,0,-1,-1,0,0,0,0,1,0,0,0,1,0,0,-1,1,0,0,-1,1,-1,0,-1,2,-1,0,-2,2,-1,
%T 1,-2,3,-2,1,-3,4,-2,2,-4,5,-3,3,-5,6,-5,4,-6,9,-6,5,-9,10,-8,8,-11,
%U 13,-11,10,-14,17,-14,13,-19,21,-18,18,-23,26,-24,23,-29,34,-30,29,-38,41,-38,39
%N Expansion of Product_{k>=2} 1/(1 + x^k).
%C The difference between the number of partitions of n into an even number of parts > 1 and the number of partitions of n into an odd number of parts > 1.
%C Convolution inverse of A025147.
%H <a href="/index/Par#part">Index entries for related partition-counting sequences</a>
%F G.f.: Product_{k>=2} 1/(1 + x^k).
%F a(n) = (-1)^n * (A000700(n) - A000700(n-1)), for n > 0. - _Vaclav Kotesovec_, Jun 06 2018
%F a(n) ~ (-1)^n * Pi * exp(Pi*sqrt(n/6)) / (2^(13/4) * 3^(3/4) * n^(5/4)). - _Vaclav Kotesovec_, Jun 06 2018
%F a(n) = A027188(n+2) - A027194(n+2). - _R. J. Mathar_, Jun 16 2018
%t nmax = 78; CoefficientList[Series[Product[1/(1 + x^k), {k, 2, nmax}], {x, 0, nmax}], x]
%Y Cf. A000700, A002865, A025147, A027349, A078616, A081362.
%K sign
%O 0,25
%A _Ilya Gutkovskiy_, Jan 22 2018