Column 3 of triangle A135902.

Terms

a(0) =1a(1) =4a(2) =24a(3) =186a(4) =1736a(5) =18754a(6) =228658a(7) =3092316a(8) =45802294a(9) =735881882a(10) =12727541778a(11) =235515880084