题解 | #尼科彻斯定理#，可以的

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int count  = 1;
            for (int i = 0,j = 0; i < a; i++,j += 2) {
                count += j;
            }
            StringBuilder builder = new StringBuilder();
            int result = count;
            for (int i = 0; i < a - 1; i++) {
                builder.append(result + "+");
                result += 2;
            }
            builder.append(result);
            System.out.println(builder);
        }
    }
}