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Expansion of Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_2(k)).
3

%I #18 Oct 27 2018 01:08:31

%S 1,-2,-8,-2,30,110,92,-182,-976,-2064,-1488,3714,17618,35814,37680,

%T -25278,-216910,-541538,-819268,-480334,1441634,5924858,12518720,

%U 16883366,7972200,-32275008,-120780700,-250726492,-349220282,-229745138,424373412,1958370998,4418456156

%N Expansion of Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_2(k)).

%H Seiichi Manyama, <a href="/A320972/b320972.txt">Table of n, a(n) for n = 0..10000</a>

%o (PARI) N=99; x='x+O('x^N); Vec(prod(k=1, N, ((1-x^k)/(1+x^k))^sigma(k, 2)))

%Y Convolution inverse of A301556.

%Y Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_b(k)): A320908 (b=0), A320971 (b=1), this sequence (b=2).

%Y Cf. A001157, A288389, A288422.

%K sign

%O 0,2

%A _Seiichi Manyama_, Oct 25 2018