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%I #17 Oct 28 2018 10:47:07
%S 1,-2,-8,-22,294,24982,1372372,10145326,-38651841784,-21995644478504,
%T -5088041946350856,29713279339187796814,155715351422115081062330,
%U 370606511915720675179342334,-12360092915168107023209454901320
%N a(n) = [x^n] Product_{k>=1} ((1 - x^k)/(1 + x^k))^sigma_n(k).
%H Seiichi Manyama, <a href="/A321068/b321068.txt">Table of n, a(n) for n = 0..80</a>
%t Table[SeriesCoefficient[Product[((1 - x^k)/(1 + x^k))^DivisorSigma[n, k], {k, 1, n}], {x, 0, n}], {n, 0, 15}] (* _Vaclav Kotesovec_, Oct 27 2018 *)
%o (PARI) {a(n) = polcoeff(prod(k=1, n, ((1-x^k+x*O(x^n))/(1+x^k+x*O(x^n)))^sigma(k, n)), n)}
%Y Cf. A320908, A320971, A320972, A321042, A321057.
%K sign
%O 0,2
%A _Seiichi Manyama_, Oct 26 2018
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