a(n) = (-1)^(n-1)*(a(n-1) - a(n-2)), a(1)=1, a(2)=1.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =0a(6) =-1a(7) =1a(8) =2a(9) =-1a(10) =-3a(11) =2a(12) =5a(13) =-3a(14) =-8a(15) =5a(16) =13a(17) =-8a(18) =-21a(19) =13a(20) =34a(21) =-21a(22) =-55a(23) =34a(24) =89a(25) =-55a(26) =-144a(27) =89a(28) =233a(29) =-144