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A281357 G.f.: (Product_{j>=1} 1/(1-q^j)^2 + Product_{j>=1} 1/(1-q^(2*j)))/2. 0
1, 1, 3, 5, 11, 18, 34, 55, 95, 150, 244, 376, 588, 885, 1340, 1978, 2922, 4235, 6130, 8745, 12442, 17501, 24533, 34075, 47156, 64756, 88594, 120420, 163075, 219595, 294652, 393407, 523468, 693465, 915681, 1204329, 1579087, 2063035, 2687440, 3489365, 4518083, 5832448 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Roland Bacher, P. De La Harpe, Conjugacy growth series of some infinitely generated groups, hal-01285685v2, 2016.
FORMULA
a(n) ~ exp(2*Pi*sqrt(n/3)) / (8 * 3^(3/4) * n^(5/4)). - Vaclav Kotesovec, Oct 13 2017
MATHEMATICA
CoefficientList[Series[(1/QPochhammer[x, x]^2 + 1/QPochhammer[x^2, x^2])/2, {x, 0, 50}], x] (* Vaclav Kotesovec, Oct 13 2017 *)
PROG
(PARI) nn = 50; Vec((prod(j=1, nn, 1/(1-q^j)^2) + prod(j=1, nn, 1/(1-q^(2*j))))/2 + O(q^nn)) \\ Michel Marcus, Oct 13 2017
CROSSREFS
Sequence in context: A298121 A244473 A023597 * A320789 A269628 A162891
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 22 2017
EXTENSIONS
More terms from Ilya Gutkovskiy, Feb 02 2017
STATUS
approved

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Last modified March 29 08:13 EDT 2024. Contains 371265 sequences. (Running on oeis4.)