Expansion of log(1 + tanh(x))/cos(x).

Terms

a(0) =0a(1) =1a(2) =-1a(3) =3a(4) =-4a(5) =25a(6) =-61a(7) =427a(8) =-1184a(9) =12465a(10) =-49201a(11) =555731a(12) =-2361844a(13) =35135945a(14) =-191422141a(15) =2990414715a(16) =-17147588384a(17) =329655706465