P7018 [CERC2013] Bus

A bus with $n$ passengers opens its door at the bus stop. Exactly half of its passengers and an additional half of a passenger get out. On the next stop, again, half of the passengers plus half of a passenger leave the bus. This goes on for $k$ stops in total. Knowing that the bus leaves the last stop empty, and that no one was hurt during the trip, determine the initial number $n$ of people in the bus.

The first line of input contains the number of test cases $T$. The descriptions of the test cases follow: The only line of each test case contains the number of stops $k$, $1 \leq k \leq 30$.

For each test case, output a single line containing a single integer—the initial number of bus passengers.

Time limit: 1000 ms, Memory limit: 1048576 kB. Central Europe Regional Contest (CERC) 2013