E.g.f. arctan(log(1+tanh(x))).

Terms

a(0) =0a(1) =1a(2) =-1a(3) =-2a(4) =14a(5) =-6a(6) =-406a(7) =2220a(8) =13768a(9) =-280224a(10) =501824a(11) =34875600a(12) =-394160416a(13) =-3296452368a(14) =129418793776a(15) =-532969950240