How do I get the index in the sequence from the Fibonacci number? 0 1 1 2 3 5 8 13 21 34... For example N(3) = 4 (starting from zero) N(34) = 9 (starting from zero) .. N(X) = ? I've seen an equation in wikipedia ![alt text][1] There are other ways to compute it? [1]: https://upload.wikimedia.org/math/4/6/2/462ccc015b0168c2838cc212ccea259e.png