a(n) = Sum_{i=n-6..n-1} (-1)^i * a(i), a(1)=1, a(2)=1, a(3)=1, a(4)=1, a(5)=1, a(6)=1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =0a(7) =1a(8) =1a(9) =1a(10) =1a(11) =1a(12) =1a(13) =0a(14) =-1a(15) =1a(16) =1a(17) =1a(18) =1a(19) =1a(20) =2a(21) =-1a(22) =-3a(23) =1a(24) =1a(25) =1a(26) =1a(27) =2a(28) =5a(29) =-3