T(n,n-3), array T as in A047140.

Terms

a(0) =1a(1) =5a(2) =19a(3) =68a(4) =250a(5) =935a(6) =3473a(7) =12850a(8) =48066a(9) =181540a(10) =686960a(11) =2600830a(12) =9893064a(13) =37819055a(14) =144917337a(15) =556011134a(16) =2138565128a(17) =8248348136a(18) =31873293528a(19) =123320614254a(20) =477883163716