A013420 - OEIS

%I #6 May 05 2021 11:53:46

%S 1,0,0,40,0,108000,1232000,1647734400,57657600000,85927162048000,

%T 6053574009600000,11452742596189440000,1349295190949488640000,

%U 3261229190521061760000000,577775664177165642240000000

%N sec(arcsin(x)-arcsinh(x))=1+40/6!*x^6+108000/10!*x^10+1232000/12!*x^12...

%t With[{nn=30},Take[CoefficientList[Series[Sec[ArcSin[x]-ArcSinh[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, May 05 2021 *)

%K nonn

%O 0,4

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