Matrix square of triangle W = A136231; also equals P^6, where P = triangle A136220.

Terms

a(0) =1a(1) =6a(2) =1a(3) =48a(4) =12a(5) =1a(6) =495a(7) =150a(8) =18a(9) =1a(10) =6338a(11) =2160a(12) =306a(13) =24a(14) =1a(15) =97681a(16) =36103a(17) =5643a(18) =516a(19) =30a(20) =1a(21) =1767845a(22) =694079a(23) =115917a(24) =11592a(25) =780a(26) =36a(27) =1a(28) =36839663a(29) =15164785