func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int a[n];     a[0] = 1;     a[1] = 5;     a[2] = 13;     a[3] = 25;     for (int i = 4; i < n; i++) {       a[i] = a[i - 1] + 4 * (i);     }     cout << a[n - 1] << endl;     return 0;   }   