T(n,n+3), array T as in A047120.

Terms

a(0) =1a(1) =4a(2) =15a(3) =56a(4) =211a(5) =798a(6) =3030a(7) =11550a(8) =44193a(9) =169652a(10) =653158a(11) =2521038a(12) =9752516a(13) =37802636a(14) =146792136a(15) =570924940a(16) =2223730395a(17) =8672669484a(18) =33864089798a(19) =132372227670a(20) =517947357111