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A321068
a(n) = [x^n] Product_{k>=1} ((1 - x^k)/(1 + x^k))^sigma_n(k).
2
1, -2, -8, -22, 294, 24982, 1372372, 10145326, -38651841784, -21995644478504, -5088041946350856, 29713279339187796814, 155715351422115081062330, 370606511915720675179342334, -12360092915168107023209454901320
OFFSET
0,2
LINKS
MATHEMATICA
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 *)
PROG
(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)}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Oct 26 2018
STATUS
approved