#include <iostream>
using namespace std;
int main(void)
{
int n, t;
while(cin >> t)
{
while(t--)
{
cin >> n;
int p = 1, q = 3;
for(int i = 2; i < n; i++)
{
int y = q;
q = p * 2 + q;
p = y;
}
if(n == 1)
cout << p << endl;
else if(n == 2)
cout << q << endl;
else
cout << q << endl;
}
}
return 0;
}
HDU-2190 悼念512汶川大地震遇难同胞——重建希望小学
原文：http://www.cnblogs.com/limyel/p/7159945.html