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

Terms

a(0) =1a(1) =2a(2) =0a(3) =-5a(4) =-8a(5) =0a(6) =21a(7) =34a(8) =0a(9) =-89a(10) =-144a(11) =0a(12) =377a(13) =610a(14) =0a(15) =-1597a(16) =-2584a(17) =0a(18) =6765a(19) =10946a(20) =0a(21) =-28657a(22) =-46368a(23) =0a(24) =121393a(25) =196418a(26) =0a(27) =-514229a(28) =-832040a(29) =0