a(n) = T(n,n-3), array T as in A055450.

Terms

a(0) =1a(1) =4a(2) =9a(3) =14a(4) =56a(5) =230a(6) =965a(7) =4120a(8) =17846a(9) =78244a(10) =346605a(11) =1549030a(12) =6976140a(13) =31628838a(14) =144250962a(15) =661352970a(16) =3046379300a(17) =14091723450a(18) =65432979080a(19) =304880016970