打表拿下

2,6,14,30,62,126,254,510,1022,2046

#include<iostream>
#include<cmath>
using namespace std;
int a[10]={2,6,14,30,62,126,254,510,1022,2046};
int main(){
    int n;
    cin>>n;
    cout<<a[n-1];
}