Column 1 of triangle A135880.

Terms

a(0) =1a(1) =2a(2) =7a(3) =34a(4) =215a(5) =1698a(6) =16220a(7) =182714a(8) =2378780a(9) =35219202a(10) =585245185a(11) =10797322816a(12) =219163958124