it is shorthand in determining the n^th term of fibonacci sequence without dealing with the recursive process.
The Fibonacci numbers: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...
F_{n+1}=F_n+F_{n−1}
Formula for Fibonacci numbers
Given a number n, print n-th Fibonacci Number.
Examples:
Input : n = 2
Output : 1
Input : n = 9
Output : 34