Amy has a 2 \times 10 puzzle grid which she can use 1 \times 1 and 1 \times 2 (1 vertical, 2 horizontal) tiles to cover. How many ways can she exactly cover the grid without any tiles overlapping and without rotating the tiles?
Amy has a 2 \times 10 puzzle grid which she can use 1 \times 1 and 1 \times 2 (1 vertical, 2 horizontal) tiles to cover. How many ways can she exactly cover the grid without any tiles overlapping and without rotating the tiles?