ZOJ Problem Set - 2547
In how many ways can you tile a 3xn rectangle with 2x1 dominoes?
Here is a sample tiling of a 3x12 rectangle.
InputInput consists of several test cases followed by a line containing -1. Each test case is a line containing an integer 0 ≤ n ≤ 30.
OutputFor each test case, output one integer number giving the number of possible tilings.
2 8 12 -1
3 153 2131
Source: University of Waterloo Local Contest 2005.09.24