hdoj：2042

Posted 2020-08-16

#include <iostream>
using namespace std;

int main()
{
    int n,a;
    while (cin >> n)
    {
        while (n--)
        {
            cin >> a;
            long num = pow(2, a) + 2;
            cout << num << endl;
        }
    }
}

 

a(n) = 2*a(n-1) -2

a(n) -2 = 2*{a(n-1) -2}

a(n) = 2^n + 2