Codeforces Buttons

题目分析：数学问题，依次计算

import java.util.Scanner;public class Buttons {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);while(scanner.hasNext()) {int n = scanner.nextInt();int sum = 0;int count = 0;for(int i = n; i >= 1; i--) {sum += (i -1) * (count + 1) + 1;count++;}System.out.println(sum);}}}