Expansion of e.g.f. exp(arctan(1+2*x) - Pi/4).

Terms

a(0) =1a(1) =1a(2) =-1a(3) =-1a(4) =17a(5) =-95a(6) =175a(7) =3775a(8) =-63775a(9) =533825a(10) =108575a(11) =-98151425a(12) =2037293425a(13) =-20945772575a(14) =-111991234225