T(n,n-1), array T as in A047130.

Terms

a(0) =1a(1) =2a(2) =5a(3) =14a(4) =28a(5) =84a(6) =272a(7) =1679a(8) =5564a(9) =19613a(10) =70504a(11) =311534a(12) =1172750a(13) =4405073a(14) =16581264a(15) =67108040a(16) =260573610a(17) =1004778126a(18) =3867996120a(19) =15289911196a(20) =59854486782a(21) =233437968413a(22) =909025875014