T(2n,n), array T as in A047140.

Terms

a(0) =1a(1) =3a(2) =13a(3) =68a(4) =395a(5) =2383a(6) =14628a(7) =91002a(8) =572629a(9) =3635105a(10) =23230955a(11) =149252778a(12) =963125552a(13) =6238012172a(14) =40529533578a(15) =264038158806