Expansion of e.g.f.: sec(x) + 2*tan(x).

Terms

a(0) =1a(1) =2a(2) =1a(3) =4a(4) =5a(5) =32a(6) =61a(7) =544a(8) =1385a(9) =15872a(10) =50521a(11) =707584a(12) =2702765a(13) =44736512a(14) =199360981a(15) =3807514624a(16) =19391512145a(17) =419730685952