题解 | #尼科彻斯定理#

(a1+a1+2(n-1))* n/2=n3 首项加末项项数除2==》n3=a1 n+n2-n==>n2=a1+n-1==>a1=n2-n+1

import java.util.*;

public class Main{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            int a = (int)Math.pow(n,2)-n+1;
            String str = a+"";
            for(int i=1;i<n;i++){
                a = a+2;
                str = str+"+"+a;
            }
            System.out.println(str);
        }
        
    }
}