尼科彻斯定理

import java.util.Scanner;

public class Main 
{
    public String getSequeOddNum(int m)
    {
        int low;
        if (m % 2 != 0) {
            low = m * m - 2*(m/2);
        }
        else {
            low = m * m - 1 - (m-1)/2*2;
        }

        StringBuilder s = new StringBuilder().append(low);
        for (int i = 1; i < m; i++) {
            s.append("+").append(low + i*2);
        }
        return s.toString();
    }

    public Main() 
    {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) 
        {
            int m = in.nextInt();
            String result = getSequeOddNum(m);
            System.out.println(result);
        }
    }

    public static void main(String[] args) 
    {
        Main solution = new Main();
    }
}