Expansion of log(1+x)/cosh(log(1+x)).

Terms

a(0) =0a(1) =1a(2) =-1a(3) =-1a(4) =12a(5) =-56a(6) =180a(7) =-204a(8) =-2688a(9) =26496a(10) =-103680a(11) =-679680a(12) =18627840a(13) =-229063680a(14) =1990759680a(15) =-12036729600a(16) =40874803200a(17) =-365550796800