A013514 - OEIS

%I #14 Dec 25 2017 14:35:03

%S 1,12,15232,128432832,3951670227712,322851365262723072,

%T 57788996387839852122112,19922979338554898934445228032,

%U 12060985210981195011358156168364032,11959494452317925171268058230736426893312,18398266125441128266076209600703368534212739072

%N sec(sec(x)-sech(x)) = 1+12/4!*x^4+15232/8!*x^8+128432832/12!*x^12...

%p A013514 := proc(n)

%p         sec(sec(x)-sech(x)) ;

%p         coeftayl( %,x=0,4*n) ;

%p         %*(4*n)! ;

%p end proc: # _R. J. Mathar_, Dec 16 2011

%t With[{nn=40},Take[CoefficientList[Series[Sec[Sec[x]-Sech[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,4}]] (* _Harvey P. Dale_, Dec 25 2017 *)

%K nonn

%O 0,2

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E More terms from _N. J. A. Sloane_, Dec 17 2011