T(2n,n), array T given by A047000.

Terms

a(0) =1a(1) =2a(2) =4a(3) =14a(4) =60a(5) =286a(6) =1456a(7) =7752a(8) =42636a(9) =240350a(10) =1381380a(11) =8064030a(12) =47682960a(13) =284997384a(14) =1719031840a(15) =10450528048a(16) =63967345068a(17) =393895175646