k=2 column of A038719.

Terms

a(0) =2a(1) =18a(2) =110a(3) =570a(4) =2702a(5) =12138a(6) =52670a(7) =223290a(8) =931502a(9) =3842058a(10) =15718430a(11) =63928410a(12) =258885902a(13) =1045076778a(14) =4208939390a(15) =16921719930a(16) =67944897902a(17) =272553908298