求 1+2!+3!+...+20!的和

package cskaoyan;
 
public class cskaoyan21 {
    @org.junit.Test
    public void sum() {
        int mix = 1;
        int max = 20;
        long total = 0;
 
        for (int i = mix; i <= max; i++) {
            total += factorial(i);
        }
 
        System.out.println(total);
    }
 
    private long factorial(long number) {
        if (number == 1 || number == 0) {
            return 1;
        } else {
            return number * factorial(number - 1);
        }
    }
}