|
%I #11 Jul 18 2013 15:35:10
%S 1,1,3,15,89,685,6331,67851,833265,11509209,176580211,2980609863,
%T 54883547465,1094804661509,23519070268331,541334395140675,
%U 13290451105971425,346691343404639153,9575683088728787683,279175712231827548543,8567653762387524327225
%N E.g.f.: 1/(cos(x) - x*cosh(x)).
%C Radius of convergence of e.g.f. is |x| < r where r = 0.6516970063076... satisfies cosh(r) = cos(r)/r.
%H Vincenzo Librandi, <a href="/A205576/b205576.txt">Table of n, a(n) for n = 0..200</a>
%F a(n) ~ n!/((sin(r)+cosh(r)+sinh(r)*r)*r^(n+1)), where r = 0.6516970063... is the root of the equation r*cosh(r) = cos(r). - _Vaclav Kotesovec_, Jun 27 2013
%e E.g.f.: A(x) = 1 + x + 3*x^2/2! + 15*x^3/3! + 89*x^4/4! + 685*x^5/5! +...
%t CoefficientList[Series[1/(Cos[x]-x*Cosh[x]), {x, 0, 20}], x]* Range[0, 20]! (* _Vaclav Kotesovec_, Jun 27 2013 *)
%o (PARI) {a(n)=n!*polcoeff(1/(cos(x+x*O(x^n))-x*cosh(x+x*O(x^n))),n)}
%K nonn
%O 0,3
%A _Paul D. Hanna_, Jan 29 2012
|
