A051794 a(n)=sum((-1)^i*a(i),i=n-6..n-1), a(1)=1,a(2)=1,a(3)=1,a(4)=1,a(5)=1,a(6)=1.

1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, -1, 1, 1, 1, 1, 1, 2, -1, -3, 1, 1, 1, 1, 2, 5, -3, -7, 1, 1, 1, 0, 5, 13, -7, -15, 1, 1, 0, -5, 13, 33, -15, -31, 1, 2, -5, -23, 33, 81, -31, -63, 2, 9, -23, -79, 81, 193, -63, -128, 9, 41, -79, -239, 193, 449, -128, -265, 41, 161, -239