#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    while(cin>>n){
        if(n==0) break;
        int count=1;
        while(n!=1){
            count=count*2+2;
            n--;
        }
        printf("%d\n",count);
    }
    return 0;
}

找到规律：2*n+2  n初始值为1