Si t'as le Nord en face 2

When you're facing North ... there is the solution, given by OEIS.
A109741 Number of inequivalent (completed) n^2 X n^2 sudokus (or Sudokus).
1, 1, 2, 5472730538
OFFSET : 0,3 - meaning that there are 2 solutions for a 4x4 (2^2) grid and more than 5 billion for a 9x9
COMMENT - See A107739 for definition of a sudoku.

12|34 | | 12|34
34|12 | | 34|12
--+-- | | --+--
21|43 | | 23|41
43|21 | | 41|23