A285294 Expansion of Product_{k>=1} (1 + x^(3*k))^(3*k) / (1 + x^k)^k.

1, -1, -1, 1, -2, -3, 7, -4, -1, 20, -9, -15, 45, -39, -38, 95, -81, -99, 244, -196, -188, 538, -371, -421, 1256, -823, -820, 2575, -1672, -1904, 5367, -3714, -3861, 10555, -7362, -8159, 21391, -14975, -15592, 41654, -28293, -30748, 82026, -54899, -57331, 155933

Offset

0,5

Links

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Mathematica

nmax = 50; CoefficientList[Series[Product[(1 + x^(3*k))^(3*k) / (1 + x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 16 2017 *)

Crossrefs

Product_{k>=1} (1 + x^(m*k))^(m*k) / (1 + x^k)^k: A284628 (m=2), this sequence (m=3), A285295 (m=4).

Cf. A262924.

Sequence in context: A245675 A245617 A109205 * A371258 A115630 A195795

Adjacent sequences: A285291 A285292 A285293 * A285295 A285296 A285297

Keyword

sign

Author

Seiichi Manyama, Apr 16 2017

Status

approved