a(n) = -a(n-1) - a(n-3) + a(n-4).

Terms

a(0) =1a(1) =1a(2) =-2a(3) =2a(4) =-2a(5) =5a(6) =-9a(7) =13a(8) =-20a(9) =34a(10) =-56a(11) =89a(12) =-143a(13) =233a(14) =-378a(15) =610a(16) =-986a(17) =1597a(18) =-2585a(19) =4181a(20) =-6764a(21) =10946a(22) =-17712a(23) =28657a(24) =-46367a(25) =75025a(26) =-121394a(27) =196418a(28) =-317810a(29) =514229