1/1!+1/2!+1/3!+...+1\20!

public class Sum {

private static double sum=0;
private static double j=1;
private static double k=0;


public static void main(String[] args) {

// TODO 自动生成的方法存根
for (double i = 1;i<=20;i++){
j*=i;
// sum+=j;
k+=1/j;
}
System.out.println(k);
}


}