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%I #17 Feb 13 2018 02:53:46
%S 1,5,81,2477,124513,9330485,977555697,136714167389,24639427576513,
%T 5566295195214053,1541371979776273041,513628137925507217549,
%U 202807061788804647209761,93651309146079155756811029,50008862201366935181522322225,30579839563414166184921341412413
%N Expansion of e.g.f. tan(x)/cos(sinh(x)), odd powers only.
%H G. C. Greubel, <a href="/A009756/b009756.txt">Table of n, a(n) for n = 1..232</a>
%F a(n) ~ (2*n-1)! * 4 * tan(arcsinh(Pi/2)) / (sqrt(4+Pi^2) * arcsinh(Pi/2)^(2*n)). - _Vaclav Kotesovec_, Jan 24 2015
%t nn = 20; Table[(CoefficientList[Series[Sec[Sinh[x]]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* _Vaclav Kotesovec_, Jan 24 2015 *)
%o (PARI) x='x+O('x^50); v=Vec(serlaplace(tan(x)/cos(sinh(x)))); vector((#v-1)\2 ,n,v[2*n-1]) \\ _G. C. Greubel_, Feb 12 2018
%K nonn
%O 1,2
%A _R. H. Hardin_
%E Extended and signs tested by _Olivier Gérard_, Mar 15 1997
%E Changed offset to 1 by _Vaclav Kotesovec_, Jan 24 2015
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