T(n,n+3), array T as in A047140.

Terms

a(0) =1a(1) =3a(2) =9a(3) =38a(4) =96a(5) =277a(6) =1421a(7) =2464a(8) =6654a(9) =61802a(10) =293298a(11) =977440a(12) =3457374a(13) =15961755a(14) =68638807a(15) =261722656a(16) =993323854a(17) =4081202724a(18) =16722068344a(19) =65831346572a(20) =256639112606