Column 1 of triangle A115085.

Terms

a(0) =1a(1) =2a(2) =5a(3) =21a(4) =102a(5) =579a(6) =3601a(7) =24426a(8) =176858a(9) =1359906a(10) =10996740a(11) =93136545a(12) =821734072a(13) =7529402477a(14) =71404315785a(15) =699210393923