A261637 Expansion of Product_{k>=0} (1+x^(3*k+1))^4.

1, 4, 6, 4, 5, 16, 24, 20, 26, 48, 56, 60, 98, 132, 130, 168, 253, 288, 324, 448, 539, 588, 780, 1000, 1086, 1304, 1690, 1916, 2205, 2812, 3274, 3648, 4507, 5396, 6018, 7200, 8674, 9680, 11250, 13616, 15425, 17532, 20962, 23988, 26960, 31868, 36836, 41164

Offset

0,2

Links

Table of n, a(n) for n=0..47.

Formula

a(n) ~ exp(2*Pi*sqrt(n)/3) / (2^(1/3) * sqrt(3) * n^(3/4)).

Mathematica

nmax=50; CoefficientList[Series[Product[(1+x^(3*k+1))^4, {k, 0, nmax}], {x, 0, nmax}], x]

Crossrefs

Cf. A261612, A261615, A261638.

Sequence in context: A014110 A266491 A323016 * A366558 A378152 A091651

Adjacent sequences: A261634 A261635 A261636 * A261638 A261639 A261640

Keyword

nonn

Author

Vaclav Kotesovec, Aug 27 2015

Status

approved