public static long getRevers(int n){ 
             long sum=0;
             long nul=1;
             for(int i=1;i <=n;i++){ 
              nul=nul*i;
              sum+=nul; 
             }
             return sum; 
    }

        static int jiecheng(int n){
        if(n == 1){
            return 1;
        }else{
            return n*jiecheng(n-1);
        }
    }
    
    static int jiechenghe(int n){
        int sum = 0;
        for(int i=n;i>0;i--){
            sum += jiecheng(i);
        } 
        return sum;
    }

System.out.println(getRevers(4));//33
System.out.println(jiechenghe(4));//33