I am trying to solve this recurrence relation using generating functions $$x\_{n+2}+x\_{n+1}+x\_n=0$$
$$x\_0 = x\_1=1$$

I have got this generating function $f\_a(x)=\frac{2x+1}{x^2+x+1}$. Since the denominator has complex roots I can't factor it. Is there a way to get the series without using complex numbers?