Sudoku is a special case of a Latin square.

A Latin square is an n x n squared table filled with different symbols in such a way that each symbol occurs exactly once in each row and exactly once in each column.

1 2
2 3
1 2 3
2 3 1
3 1 2
The name Latin square were introduced by Leonhard Euler in 1783. The numbers of Latin squares of order , 2, ... are 1, 2, 12, 576, 161280, ...
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