T(n,n), array T as in A047120.

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =36a(5) =129a(6) =471a(7) =1744a(8) =6531a(9) =24643a(10) =93541a(11) =356808a(12) =1366632a(13) =5252532a(14) =20247138a(15) =78245742a(16) =303053351a(17) =1176042891a(18) =4571690601a(19) =17799156930a(20) =69394115895a(21) =270886964569