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 A320972 Expansion of Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_2(k)). 3
 1, -2, -8, -2, 30, 110, 92, -182, -976, -2064, -1488, 3714, 17618, 35814, 37680, -25278, -216910, -541538, -819268, -480334, 1441634, 5924858, 12518720, 16883366, 7972200, -32275008, -120780700, -250726492, -349220282, -229745138, 424373412, 1958370998, 4418456156 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 PROG (PARI) N=99; x='x+O('x^N); Vec(prod(k=1, N, ((1-x^k)/(1+x^k))^sigma(k, 2))) CROSSREFS Convolution inverse of A301556. Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_b(k)): A320908 (b=0), A320971 (b=1), this sequence (b=2). Cf. A001157, A288389, A288422. Sequence in context: A063077 A245995 A085192 * A273692 A006085 A021357 Adjacent sequences:  A320969 A320970 A320971 * A320973 A320974 A320975 KEYWORD sign AUTHOR Seiichi Manyama, Oct 25 2018 STATUS approved

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Last modified January 17 18:08 EST 2020. Contains 330987 sequences. (Running on oeis4.)