题解 | #牛牛学数列4#

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int res = 0; //记录第n个数
        int sum = 0; //记录n个数的和
        for(int i = 1; i <= n; i++){
            res += i;
            sum += res;
        }
        System.out.println(sum);
    }
}