a(n) = 8*a(n-2) - 9*a(n-4).

Terms

a(0) =0a(1) =1a(2) =1a(3) =5a(4) =8a(5) =31a(6) =55a(7) =203a(8) =368a(9) =1345a(10) =2449a(11) =8933a(12) =16280a(13) =59359a(14) =108199a(15) =394475a(16) =719072a(17) =2621569a(18) =4778785a(19) =17422277a(20) =31758632a(21) =115784095a(22) =211059991a(23) =769472267a(24) =1402652240a(25) =5113721281a(26) =9321678001a(27) =33984519845a(28) =61949553848a(29) =225852667231