Column 2 of triangle A111544.

Terms

a(0) =1a(1) =3a(2) =15a(3) =99a(4) =783a(5) =7083a(6) =71415a(7) =789939a(8) =9485343a(9) =122721723a(10) =1701224775a(11) =25156450179a(12) =395362560303