1！+2！+……+N！

[java]代码库

import java.util.*;
public class Main {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int sum = 0, i = 1;
		for(; i <= N; i++)
		{
			int s = 1;
			for(int j = 1; j <= i; j++)
				s *= j;
			sum  += s;
		}
		System.out.println(sum);
   }
}