T(2n,n-3), T given by A026769.

Terms

a(0) =1a(1) =14a(2) =127a(3) =956a(4) =6512a(5) =41786a(6) =258077a(7) =1553610a(8) =9188078a(9) =53657836a(10) =310517294a(11) =1785024568a(12) =10211000720a(13) =58198617436a(14) =330817445679