Negafibonacci numbers?

Number Theory Level 2

The Fibonacci numbers are given by

\(F(0) = 0\)
\(F(1) = 1\)
\(F(n) = F(n-1) + F(n-2).\)

So, the first few are \(0, 1, 1, 2, 3, 5, 8, 13.\)

If we generalize this to negative numbers, what is \(F(-8)?\)