Fibonacci Sequence C# with Example

You can calculate a number in the Fibonacci sequence using recursion. 
Following the math theory of F(n) = F(n-2) + F(n-1), for any i > 0, 
// Returns the i'th Fibonacci number 
public int fib(int i) { 
if(i <= 2) { 
// Base case of the recursive function. 
// i is either 1 or 2, whose associated Fibonacci sequence numbers are 1 and 1. 
return 1; 
} 
// Recursive case. Return the sum of the two previous Fibonacci numbers. 
// This works because the definition of the Fibonacci sequence specifies 
// that the sum of two adjacent elements equals the next element. 
return fib(i - 2) + fib(i - 1); 
} 
fib(10); // Returns 55