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For the final challenge, Bowser asks, “For which integers n, does there exist a shape which can be tiled using 2 × 1dominoes in exactly n different ways?” |
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Answer» All NATURAL Numbers ![]() This CONSTRUCTION can actually be generalised to any n. For n = 5 we havethe following shape (with four holes). ![]() Call a column strong if it has two vertical dominoes. Out of the five columnsindicated, at least one must be strong. But as soon as we CHOOSE a strongcolumn, the tiling is forced and no other columns can also be strong. Forexample, if the fourth column is strong, the following tiling is forced. ![]() Since there were five POSSIBLE choices of strong columns, there are exactlyfive ways to tile the shape. By similar arguments, for all natural numbers n,there exists a shape which can be tiled by dominoes in exactly n ways. |
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