Sixth column of triangle A055252.

Terms

a(0) =1a(1) =9a(2) =48a(3) =198a(4) =699a(5) =2223a(6) =6562a(7) =18324a(8) =49029a(9) =126837a(10) =319332a(11) =786258a(12) =1900351a(13) =4521771a(14) =10616598a(15) =24641280a(16) =56622825a(17) =128974545a(18) =291503800a(19) =654311070a(20) =1459617411a(21) =3238002279a(22) =7147093578a(23) =15703473708a(24) =34359737869a(25) =74893491693