T(n,n-3), array T as in A047089.

Terms

a(0) =1a(1) =4a(2) =13a(3) =38a(4) =98a(5) =531a(6) =1912a(7) =8138a(8) =31418a(9) =126393a(10) =495376a(11) =1962086a(12) =7714610a(13) =30417808a(14) =119689616a(15) =471372482a(16) =1855574610a(17) =7307585933a(18) =28780361988a(19) =113386055388a(20) =446810002208