the Fibonacci sequence are series of numbers:, such that each number is the sum of the two preceding ones, starting from 0. 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ... The next number is found by adding up the two numbers before it.
F 0 = 0, F1= 1, and Fn = Fn-1 + Fn-2, for n > 1.