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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..80

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

Cf. A320908, A320971, A320972, A321042, A321057.

Sequence in context: A151356 A238530 A303287 * A158466 A065694 A178129

Adjacent sequences:  A321065 A321066 A321067 * A321069 A321070 A321071

KEYWORD

sign

AUTHOR

Seiichi Manyama, Oct 26 2018

STATUS

approved

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Last modified August 12 11:29 EDT 2020. Contains 336438 sequences. (Running on oeis4.)