A009709 - OEIS

%I #22 Jan 27 2014 09:13:00

%S 1,1,17,593,19425,1598177,158823537,20206883505,3739345763009,

%T 800168319488705,218377697922437073,71589148444259595281,

%U 27561852243967184213153,12547454880768646146119585

%N E.g.f. tan(tan(x)/cosh(x)), odd powers only.

%H Vincenzo Librandi, <a href="/A009709/b009709.txt">Table of n, a(n) for n = 1..100</a>

%e tan(tan(x)/cosh(x)) = x + 1/6*x^3 + 17/120*x^5 + 593/5040*x^7 + ...

%t With[{nn=30},Take[CoefficientList[Series[Tan[Tan[x]/Cosh[x]],{x,0,nn}],x]Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, May 06 2012 *)

%K nonn

%O 1,3

%A _R. H. Hardin_

%E Extended and signs tested Mar 15 1997 by _Olivier Gérard_.