A positive integer ω is a Fibonacci number if and only if one of 5ω2 + 4 and 5ω2 - 4 is a perfect square.
See The Faboulous Fibonacci Numbers for more.
A positive integer ω is a Fibonacci number if and only if one of 5ω2 + 4 and 5ω2 - 4 is a perfect square.
See The Faboulous Fibonacci Numbers for more.