Second column of triangle in A235595.

Terms

a(0) =0a(1) =0a(2) =2a(3) =9a(4) =40a(5) =195a(6) =1056a(7) =6321a(8) =41392a(9) =293607a(10) =2237920a(11) =18210093a(12) =157329096a(13) =1436630091a(14) =13810863808a(15) =139305550065