Expansion of e.g.f. log(cosh(x) + arctanh(x)).

Terms

a(0) =0a(1) =1a(2) =0a(3) =1a(4) =-4a(5) =33a(6) =-168a(7) =1377a(8) =-9504a(9) =99649a(10) =-930560a(11) =11796673a(12) =-137207552a(13) =2017677153a(14) =-28086102016a(15) =471591223841