Column 2 of triangle A111553.

Terms

a(0) =1a(1) =3a(2) =16a(3) =116a(4) =1016a(5) =10176a(6) =113216a(7) =1375456a(8) =18047296a(9) =253815936a(10) =3805221376a(11) =60558070016