Expansion of e.g.f. exp(3*x)*(sec(x) + tan(x)).

Terms

a(0) =1a(1) =4a(2) =16a(3) =65a(4) =272a(5) =1189a(6) =5506a(7) =27365a(8) =147512a(9) =868129a(10) =5589646a(11) =39309965a(12) =300724652a(13) =2489776969a(14) =22192420786a(15) =211923843365