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%I #24 Feb 13 2018 04:06:16
%S 0,2,20,438,17128,1048874,92901500,11253292638,1788824156368,
%T 361485870772562,90552477245862884,27548125826770266630,
%U 10006652421435397898680,4278388540712731489923194,2127009769120013449890941516,1216712823253198094167750050990
%N Expansion of e.g.f. tan(x)*tan(sinh(x)), even powers only.
%H G. C. Greubel, <a href="/A009749/b009749.txt">Table of n, a(n) for n = 0..230</a>
%F a(n) ~ (2*n)! * 4 * tan(arcsinh(Pi/2)) / (sqrt(4+Pi^2) * arcsinh(Pi/2)^(2*n+1)). - _Vaclav Kotesovec_, Jan 24 2015
%t With[{nn=30},Take[CoefficientList[Series[Tan[x]*Tan[Sinh[x]],{x,0,nn}], x]Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Nov 30 2011 *)
%o (PARI) x='x+O('x^50); v=Vec(serlaplace(tan(x)*tan(sinh(x)))); concat([0], vector(#v\2,n,v[2*n-1])) \\ _G. C. Greubel_, Feb 12 2018
%K nonn
%O 0,2
%A _R. H. Hardin_
%E Extended and signs tested by _Olivier Gérard_, Mar 15 1997
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