Column 2 of triangle A109152.

Terms

a(0) =1a(1) =3a(2) =6a(3) =24a(4) =102a(5) =516a(6) =2814a(7) =16752a(8) =106026a(9) =712260a(10) =5027190a(11) =37158600a(12) =286141638a(13) =2289018708a(14) =18961164774a(15) =162271001760