T(n,n-2), array T as in A047150.

Terms

a(0) =1a(1) =4a(2) =13a(3) =46a(4) =162a(5) =588a(6) =2175a(7) =8042a(8) =30050a(9) =112859a(10) =426682a(11) =1622775a(12) =6191928a(13) =23709735a(14) =91044994a(15) =350563516a(16) =1353275024a(17) =5234851541a(18) =20287972487a(19) =78757772777a(20) =306202563769