A square tablecloth is coloured in. Colour the squares so that
each square is the same colour as all the symmetrically placed
squares and a different colour from the rest of the squares. This
means that the tablecloth will look the same if it is turned around
or turned over.
How many colours do you need for table cloths of side 3 x 3, 5 x 5,
7 x 7, 9x9 squares.
Prove that for an n x n tablecloth (where n is odd) the number of
colours needed is ...
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