%I #6 Feb 21 2023 11:33:02
%S 1,4,80,4288,426240,67920896,15873495040,5113806962688,
%T 2172417489305600,1176644688113041408,791421023406538096640,
%U 647183647775891247857664,632330839348840678513704960
%N sec(tanh(x)+tan(x))=1+4/2!*x^2+80/4!*x^4+4288/6!*x^6+426240/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Sec[Tanh[x]+Tan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Feb 21 2023 *)
%K nonn
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)