T(n,n-1), array T as in A047030.

Terms

a(0) =1a(1) =1a(2) =4a(3) =14a(4) =52a(5) =195a(6) =736a(7) =2789a(8) =10620a(9) =40611a(10) =155860a(11) =600002a(12) =2315912a(13) =8959834a(14) =34735000a(15) =134903491a(16) =524786380a(17) =2044434535a(18) =7975049436a(19) =31146540719a(20) =121774481668a(21) =476576304999