In how many ways can you tile a 2xn rectangle by 2x1 or 2x2 tiles? Here is a sample tiling of a 2x17 rectangle.
Input is a sequence of lines, each line containing an integer number 0 <= n <= 50.
For each line of input, output one integer number in a separate line giving the number of possible tilings of a 2xn Rectangle.
2 8 12 50
3 171 2731 750599937895083