T(n,n-3), array T given by A047020.

Terms

a(0) =1a(1) =3a(2) =7a(3) =19a(4) =37a(5) =99a(6) =586a(7) =1144a(8) =5452a(9) =22610a(10) =112227a(11) =482885a(12) =1978069a(13) =8394471a(14) =34646088a(15) =140372604a(16) =572795825a(17) =2320299903a(18) =9330259482a(19) =37549205868a(20) =150740987631a(21) =603268047310