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Expansion of Product_{i>=1, j>=1, k>=1, l>=1} (1 - x^(i*j*k*l))/(1 + x^(i*j*k*l)).
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%I #13 Nov 07 2018 17:25:27

%S 1,-2,-6,6,14,30,-14,-98,-86,-150,282,486,502,670,-1118,-1226,-4396,

%T -3814,1326,3834,20354,16330,18334,-6606,-45658,-60762,-121770,-60122,

%U -22750,160314,303638,435450,542336,162782,-45830,-1090994,-1576378,-2608146,-2408142,-988202,479834

%N Expansion of Product_{i>=1, j>=1, k>=1, l>=1} (1 - x^(i*j*k*l))/(1 + x^(i*j*k*l)).

%H Seiichi Manyama, <a href="/A321302/b321302.txt">Table of n, a(n) for n = 0..10000</a>

%F G.f.: Product_{k>=1} ((1 - x^k)/(1 + x^k))^A007426(k).

%o (PARI) \\ here b(n) is A007426.

%o b(n)={vecprod(apply(e->binomial(e+3, 3), factor(n)[,2]))}

%o seq(n)={Vec(prod(k=1, n, ((1 - x^k)/(1 + x^k) + O(x*x^n))^b(k)))} \\ _Andrew Howroyd_, Nov 06 2018

%Y Convolution inverse of A321240.

%Y Cf. A007426, A320908, A321241.

%K sign

%O 0,2

%A _Seiichi Manyama_, Nov 03 2018