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

Terms

a(0) =1a(1) =1a(2) =1a(3) =-2a(4) =0a(5) =2a(6) =1a(7) =-1a(8) =1a(9) =4a(10) =4a(11) =4a(12) =9a(13) =17a(14) =25a(15) =38a(16) =64a(17) =106a(18) =169a(19) =271a(20) =441a(21) =716a(22) =1156a(23) =1868a(24) =3025a(25) =4897a(26) =7921a(27) =12814a(28) =20736a(29) =33554