A320972 Expansion of Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_2(k)).

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

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