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

Terms

a(0) =-1a(1) =0a(2) =1a(3) =-1a(4) =-3a(5) =3a(6) =8a(7) =-9a(8) =-21a(9) =27a(10) =55a(11) =-80a(12) =-143a(13) =235a(14) =369a(15) =-685a(16) =-944a(17) =1983a(18) =2391a(19) =-5705a(20) =-5985a(21) =16320a(22) =14769a(23) =-46441a(24) =-35803a(25) =131507a(26) =84824a(27) =-370665a(28) =-194813a(29) =1040147