题解 | #尼科彻斯定理#

#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    int first;
    while (cin >> n) {
        first = n*n - n + 1;
        cout << first;
        for (int i = 1; i < n; ++i) {
            cout << "+" << first + i * 2;
        }
        cout << endl;
    }
    return 0;
}