题目描述
Phoenix has $n$ coins with weights $2^1, 2^2, \dots, 2^n$. He knows that $n$ is even.
He wants to split the coins into two piles such that each pile has exactly $\frac{n}{2}$ coins and the difference of weights between the two piles is minimized. Formally, let $a$ denote the sum of weights in the first pile, and $b$ denote the sum of weights in the second pile. Help Phoenix minimize $|a-b|$, the absolute value of $a-b$.
Input
The input consists of multiple test cases. The first line contains an integer $t$ ($1 \le t \le 100$) — the number of test cases.
The first line of each test case contains an integer $n$ ($2 \le n \le 30$; $n$ is even) — the number of coins that Phoenix has.
Output
For each test case, output one integer — the minimum possible difference of weights between the two piles.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
In the first test case, Phoenix has two coins with weights $2$ and $4$. No matter how he divides the coins, the difference will be $4-2=2$.
In the second test case, Phoenix has four coins of weight $2$, $4$, $8$, and $16$. It is optimal for Phoenix to place coins with weights $2$ and $16$ in one pile, and coins with weights $4$ and $8$ in another pile. The difference is $(2+16)-(4+8)=6$.