T(n,n-2), array T as in A047120.

Terms

a(0) =1a(1) =1a(2) =6a(3) =22a(4) =86a(5) =335a(6) =1307a(7) =5071a(8) =19664a(9) =76299a(10) =296396a(11) =1152682a(12) =4487818a(13) =17492162a(14) =68252789a(15) =266589233a(16) =1042279572a(17) =4078677195a(18) =15974343417a(19) =62614027433a(20) =245608306154a(21) =964087953123