T(n,n-3), array T as in A047030.

Terms

a(0) =1a(1) =2a(2) =4a(3) =22a(4) =100a(5) =421a(6) =1730a(7) =7000a(8) =28056a(9) =111754a(10) =443444a(11) =1755310a(12) =6937216a(13) =27389041a(14) =108067718a(15) =426244160a(16) =1680912060a(17) =6628454969a(18) =26139689490a(19) =103095008914a(20) =406671627876