Expansion of e.g.f. log(sech(x) + tanh(x)).

Terms

a(0) =0a(1) =1a(2) =-2a(3) =3a(4) =-8a(5) =45a(6) =-272a(7) =1743a(8) =-13568a(9) =125625a(10) =-1290752a(11) =14554683a(12) =-181296128a(13) =2473184805a(14) =-36501112832a(15) =579439207623