E.g.f.: sec(x)^2*tan(x)+sec(x)*tan(x)^2.

Terms

a(0) =0a(1) =1a(2) =2a(3) =8a(4) =28a(5) =136a(6) =662a(7) =3968a(8) =24568a(9) =176896a(10) =1326122a(11) =11184128a(12) =98329108a(13) =951878656a(14) =9596075582a(15) =104932671488