C++ :

#include <stdio.h>
int main()
{
 int n,a,i,sum=3;
 scanf("%d",&n);
 while(n--)
 {
  sum=3;
  scanf("%d",&a);
  for(i=0;i<a;++i)
   sum=(sum-1)*2;
  printf("%d\n",sum);
 }
}