codeforces - phoenix and balance

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fast()(ios_base::sync_with_stdio(0),cin.tie(NULL));
int main()
{
    fast();
    ll t ;
    cin>>t;
    while(t--)
    {
        ll n;
        cin>>n;
        ll sum=0, sum2=0;
        ll ara[n+2];
        for(ll i=1 ; i<=n;i++)
        {
            ara[i]=pow(2,i);
            sum+=ara[i];
            if(i<n/2 || i==n)sum2+=ara[i];
        }
        sum= sum-sum2;
        cout<<abs(sum-sum2)<<endl;
    }
}