%I #6 Sep 17 2023 15:25:41
%S 1,-1,-7,-121,-5167,-487441,-78804727,-18558463561,-5919443326687,
%T -2457116797560481,-1289150916753299047,-834798631079038210201,
%U -654139310316332313889807,-610085118687493622960844721
%N sech(arcsin(tan(x)))=1-1/2!*x^2-7/4!*x^4-121/6!*x^6-5167/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Sech[ArcSin[Tan[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Sep 17 2023 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)
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