T(2n,n), array T given by A047050.

Terms

a(0) =1a(1) =2a(2) =9a(3) =48a(4) =275a(5) =1652a(6) =10150a(7) =63282a(8) =398746a(9) =2533674a(10) =16205319a(11) =104195452a(12) =672838453a(13) =4360534510a(14) =28346553454a(15) =184759124740