E.g.f.: (sin x + cos 2x) / cos 3x.

Terms

a(0) =1a(1) =1a(2) =5a(3) =26a(4) =205a(5) =1936a(6) =22265a(7) =297296a(8) =4544185a(9) =78098176a(10) =1491632525a(11) =31336418816a(12) =718181418565