a(n) = T(n,2n-8), T given by A027023.

Terms

a(0) =1a(1) =1a(2) =5a(3) =17a(4) =57a(5) =193a(6) =649a(7) =2161a(8) =7113a(9) =23137a(10) =74417a(11) =236913a(12) =747401a(13) =2339137a(14) =7270189a(15) =22460801a(16) =69031105a(17) =211206529a(18) =643684485a(19) =1955082321a(20) =5920720729a(21) =17884040961a(22) =53898818389a(23) =162120056257a(24) =486791503521