T(n,n-3), array T as in A047060.

Terms

a(0) =1a(1) =4a(2) =14a(3) =50a(4) =180a(5) =651a(6) =2387a(7) =8833a(8) =32981a(9) =123991a(10) =468476a(11) =1778564a(12) =6779824a(13) =25939287a(14) =99558312a(15) =383146247a(16) =1478074248a(17) =5714228324a(18) =22133961135a(19) =85885304838a(20) =333778557727