T(n,n-2), array T given by A047020.

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =38a(5) =66a(6) =293a(7) =1144a(8) =5452a(9) =22610a(10) =89617a(11) =370658a(12) =1495184a(13) =5933517a(14) =23790663a(15) =94871091a(16) =376066283a(17) =1494417598a(18) =5930990794a(19) =23487622433a(20) =93066819110a(21) =368664549287