Fibonacci number
n mathematics, the Fibonacci numbers are the numbers in the following integer sequence, called the Fibonacci sequence, and characterized by the fact that every number after the first two is the sum of the two preceding ones.
0,1,1,2,3,5,8,13,21........
The sequence Fn of Fibonacci numbers is defined by the recurrence relation:
Fn = Fn-1 +Fn-2;
