a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = 0, a(1) = -1, a(2) = 0, a(3) = 1.

Terms

a(0) =0a(1) =-1a(2) =0a(3) =1a(4) =3a(5) =8a(6) =15a(7) =31a(8) =54a(9) =101a(10) =171a(11) =304a(12) =507a(13) =875a(14) =1446a(15) =2449a(16) =4023a(17) =6728a(18) =11007a(19) =18247a(20) =29766a(21) =49037a(22) =79827a(23) =130912a(24) =212787a(25) =347795a(26) =564678a(27) =920665a(28) =1493535a(29) =2430584