A012881 - OEIS

%I #6 Jul 08 2020 12:36:46

%S 1,1,1,-3,-15,5,345,889,-11263,-82167,455025,7869301,-16466703,

%T -906141171,-746021367,128450716913,480286325633,-22562588189167,

%U -150637957014303,4955964959446253,46203820378253425

%N Expansion of e.g.f.: exp(sech(x)*arcsinh(x))=1+x+1/2!*x^2-3/3!*x^3-15/4!*x^4+5/5!*x^5...

%t With[{nn=20},CoefficientList[Series[Exp[Sech[x]ArcSinh[x]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jul 08 2020 *)

%K sign

%O 0,4

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

%E Definition clarified by _Harvey P. Dale_, Jul 08 2020