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A303349 Expansion of Product_{n>=1} 1/(1 - 9*x^n)^(1/3). 3

%I #19 Apr 23 2018 18:02:53

%S 1,3,21,138,1029,7878,62751,508521,4185885,34819986,292135143,

%T 2467528563,20958538377,178846047741,1532203949982,13171424183184,

%U 113562780734352,981679181808261,8505577753517235,73846557073784937,642328501788394527

%N Expansion of Product_{n>=1} 1/(1 - 9*x^n)^(1/3).

%C This sequence is obtained from the generalized Euler transform in A266964 by taking f(n) = 1/3, g(n) = 9.

%C In general, if h > 1 and g.f. = Product_{k>=1} 1/(1 - h^2*x^k)^(1/h), then a(n) ~ h^(2*n) / (Gamma(1/h) * QPochhammer[1/h^2]^(1/h) * n^(1 - 1/h)). - _Vaclav Kotesovec_, Apr 22 2018

%H Seiichi Manyama, <a href="/A303349/b303349.txt">Table of n, a(n) for n = 0..1000</a>

%F a(n) ~ c * 3^(2*n) / n^(2/3), where c = 1 / (Gamma(1/3) * QPochhammer[1/9]^(1/3)) = 0.390040743840141117482137514... - _Vaclav Kotesovec_, Apr 22 2018

%p seq(coeff(series(mul(1/(1-9*x^k)^(1/3), k = 1..n), x, n+1), x, n), n=0..25); # _Muniru A Asiru_, Apr 22 2018

%t nmax = 20; CoefficientList[Series[Product[1/(1 - 9*x^k)^(1/3), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Apr 22 2018 *)

%Y Expansion of Product_{n>=1} 1/(1 - b^2*x^n)^(1/b): A000041 (b=1), A067855 (b=2), this sequence (b=3).

%Y Cf. A303348.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Apr 22 2018

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Last modified March 29 07:27 EDT 2024. Contains 371265 sequences. (Running on oeis4.)