

A261566


Expansion of Product_{k>=1} (1/(1 + 2*x^k))^k.


4



1, 2, 0, 6, 16, 18, 48, 94, 208, 426, 752, 1646, 3360, 6578, 13056, 26358, 53456, 105890, 211392, 424366, 850544, 1699290, 3393136, 6795646, 13601184, 27188130, 54358000, 108752870, 217552976, 435033618, 869999584, 1740145118, 3480497584
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OFFSET

0,2


LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000


FORMULA

a(n) ~ c * (2)^n, where c = Product_{j>=1} 1/(1  1/(2)^j)^(j+1) = 0.81033497534928929188778847125052151513524786804782471307090750707405...


MATHEMATICA

nmax = 40; CoefficientList[Series[Product[(1/(1 + 2*x^k))^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 40; CoefficientList[Series[Exp[Sum[(1)^k*2^k/k*x^k/(1x^k)^2, {k, 1, nmax}]], {x, 0, nmax}], x]


CROSSREFS

Cf. A071109, A255528, A261567.
Sequence in context: A110667 A129877 A307581 * A247443 A171734 A278746
Adjacent sequences: A261563 A261564 A261565 * A261567 A261568 A261569


KEYWORD

sign


AUTHOR

Vaclav Kotesovec, Aug 24 2015


STATUS

approved



