Expansion of e.g.f.: tan(tanh(log(1+x))).

Terms

a(0) =0a(1) =1a(2) =-1a(3) =2a(4) =-6a(5) =16a(6) =0a(7) =-568a(8) =7504a(9) =-78248a(10) =739080a(11) =-6314848a(12) =44072688a(13) =-125928464a(14) =-3754236304a(15) =114500663552