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(n2 is n squared)

For a table clothe of rotational symmetry of 4 a 5x5 has 7 diferent colours. To wotk it out you follow this formula: ((n2-1)/4)+1. This is because is we take out the square in the middle every other colour has four other duplicate because it has a rotational symmetry of 4. So n2 -1 is the whole grid minus the middle. If we divide this by 4 we get the amount of different colour apart from the middle, which is 6. At the end we add the middle square and we end with 7.