n = 2 chứ :/

Code C++

#include <bits/stdc++.h>
using namespace std;
signed main() {
	freopen("Bai2_10.inp","r",stdin);
	freopen("Bai2_10.out","w",stdout);
	#define int long long
	int n;
	cin>>n;
	cout<<(n+1)*(n+1);
}

#include <bits/stdc++.h>
using namespace std;
unsigned long long int n, to;
int main() 
{
    cin >> n;
    for(int a = 0; a < n; a++)
    {
        to += (2*a) + 1;
    }
    cout << to;
}

$#khanhtaon$