A D997: Natural number sequence $F : \mathbb{N} \to \mathbb{N}$ is the Fibonacci natural number sequence if and only if

(1)	$F_0 = 0$
(2)	$F_1 = 1$
(3)	$\forall \, n \geq 2 : F_n = F_{n - 1} + F_{n - 2}$