计算 1+1/2!+1/3!+1/4!+...1/20!=?

public class jia {

    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        double jiecheng=1;
        double sum=0;
        int j=0;
        for(int i=1;i<20;i++)
        {
            do
            {
                j++;
                jiecheng=jiecheng*j;
            }
            while(j<i);
            //System.out.println(jiecheng);
            sum=sum+1jiecheng;
            }
        System.out.println("1+1/2!+1/3!+1/4!+...1/20!="+sum);

    }

}