Column 2 of triangle A135880.

Terms

a(0) =1a(1) =3a(2) =15a(3) =99a(4) =814a(5) =8057a(6) =93627a(7) =1252752a(8) =19003467a(9) =322722064a(10) =6071897378a(11) =125464556309