T(2n,n), array T as in A054134.

Terms

a(0) =1a(1) =4a(2) =18a(3) =97a(4) =570a(5) =3489a(6) =21810a(7) =138044a(8) =881098a(9) =5658793a(10) =36520068a(11) =236619717a(12) =1538134272a(13) =10026366588a(14) =65513185896a(15) =428957025672