题解 | #尼科彻斯定理#

直接字符串拼接，开始数字为 n^2 - n +1,每次加2，最后一个为n^2+n-1;

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    
    while(in.hasNextInt()){
        int num = in.nextInt();
        
        int nums = num * num;
        StringBuffer str = new StringBuffer();
        for(int i = nums - num + 1; i < nums + num ; i=i+2){
            if(i == nums + num - 1 ){
                str.append(i);
            }else{
                str.append(i + "+");
            }
        }
        System.out.println(str.toString());
    }
}