T(n,n-1), array T as in A047060.

Terms

a(0) =1a(1) =2a(2) =5a(3) =16a(4) =53a(5) =179a(6) =637a(7) =2302a(8) =8481a(9) =31553a(10) =118050a(11) =445260a(12) =1688727a(13) =6438285a(14) =24645509a(15) =94629373a(16) =364407934a(17) =1406835343a(18) =5443691793a(19) =21106577597a(20) =81977147966a(21) =318895294012