Consider the following iterative function:

1.      Consider the following iterative function:

int pentagonal(int n) {

int result = 0;

for (int i = 1; i <= n; i++)

result += 3 * i - 2;

return result;

 }

Rewrite the function pentagonal using recursion and add preconditions and postconditions as comments. Then prove by induction that the recursive function you wrote is correct.