public class Seatwork2{
	public static void main(String[] args){
		int sum = 0;
		for(int j =1;j<=20;j++){
			sum+=factorial(j);
		}
		System.out.println("sum = "+sum);
	}
	public static long factorial(int i){
		if(i==1){
			return 1;
		}
		return i*factorial(i-1);
	}
}

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