A321302 Expansion of Product_{i>=1, j>=1, k>=1, l>=1} (1 - x^(i*j*k*l))/(1 + x^(i*j*k*l)).
1, -2, -6, 6, 14, 30, -14, -98, -86, -150, 282, 486, 502, 670, -1118, -1226, -4396, -3814, 1326, 3834, 20354, 16330, 18334, -6606, -45658, -60762, -121770, -60122, -22750, 160314, 303638, 435450, 542336, 162782, -45830, -1090994, -1576378, -2608146, -2408142, -988202, 479834
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..10000
Programs
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PARI
\\ here b(n) is A007426. b(n)={vecprod(apply(e->binomial(e+3, 3), factor(n)[,2]))} seq(n)={Vec(prod(k=1, n, ((1 - x^k)/(1 + x^k) + O(x*x^n))^b(k)))} \\ Andrew Howroyd, Nov 06 2018
Formula
G.f.: Product_{k>=1} ((1 - x^k)/(1 + x^k))^A007426(k).