Expansion of e.g.f.: exp(tan(tanh(x))).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =-7a(6) =-47a(7) =-55a(8) =449a(9) =2897a(10) =18209a(11) =5105a(12) =-1441087a(13) =-7252983a(14) =41192817a(15) =341550201a(16) =2660018305a(17) =43255573537a(18) =-460752070079