Expansion of e.g.f.: sin(arctan(x)).

Terms

a(0) =0a(1) =1a(2) =0a(3) =-3a(4) =0a(5) =45a(6) =0a(7) =-1575a(8) =0a(9) =99225a(10) =0a(11) =-9823275a(12) =0a(13) =1404728325a(14) =0a(15) =-273922023375a(16) =0a(18) =0a(20) =0a(22) =0a(24) =0a(26) =0