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%I #9 Feb 08 2015 05:09:51
%S 0,2,8,-112,-8832,-269568,18508800,4584990720,373223424000,
%T -57291983093760,-29502109561651200,-4280300758758850560,
%U 1571738277174218588160,1306880625182819525591040
%N tanh(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4-112/6!*x^6-8832/8!*x^8...
%C Since a(18) are all terms positive. - _Vaclav Kotesovec_, Feb 08 2015
%H Vaclav Kotesovec, <a href="/A012347/b012347.txt">Table of n, a(n) for n = 0..200</a>
%F a(n) ~ sqrt(Pi) * (2*n)! / (n^(3/2) * (1 + cosh(Pi^2/2))). - _Vaclav Kotesovec_, Feb 08 2015
%t nn = 20; Table[(CoefficientList[Series[Tanh[ArcSin[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* _Vaclav Kotesovec_, Feb 08 2015 *)
%K sign
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E a(0)=0 prepended by _Vaclav Kotesovec_, Feb 08 2015
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