%I A109741
%S A109741 1,1,2,5472730538
%N A109741 Number of inequivalent (completed) n^2 X n^2 sudokus (or Sudokus).
%C A109741 See A107739 for definition of a sudoku.
%C A109741 a(2) = 2 independently computed by Gary McGuire and Hugo van der Sanden.
%C A109741 For the 9 X 9 case the allowed equivalences are: relabeling entries; 
               reflection; rotation;
%C A109741 permutation of blocks of columns 1-3, 4-6 and 7-9;
%C A109741 permutation of blocks of rows 1-3, 4-6 and 7-9;
%C A109741 permutation of columns 1-3; permutation of rows 1-3;
%C A109741 permutation of columns 4-6; permutation of rows 4-6;
%C A109741 permutation of columns 7-9; permutation of rows 7-9.
%D A109741 J.-P. Delahaye, "Le tsunami du Sudoku" in 'Pour La Science' (French Edition 
               of "Scientific American"), December 2005 pp. 144-9, Paris.
%H A109741 Bertram Felgenhauer and Frazer Jarvis, <a href="http://www.shef.ac.uk/
               ~pm1afj/sudoku/">There are 6670903752021072936960 Sudoku grids</a>
%H A109741 J. P. Grossman, <a href="http://www.mathstat.dal.ca/~jpg/sudoku/">Javascript 
               Sudoku solver</a>
%H A109741 S. Gupta, <a href="http://theory.tifr.res.in/~sgupta/sudoku/challenges.html#prime">
               Exploring the Mathematics of Su Doku</a>
%H A109741 Ed Russell and Frazer Jarvis, <a href="http://www.shef.ac.uk/~pm1afj/
               sudoku/sudgroup.html">There are 5472730538 essentially different 
               Sudoku grids</a>
%H A109741 Wikipedia, <a href="http://en.wikipedia.org/wiki/Sudoku">Sudoku</a>
%H A109741 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Sudoku.html">Sudoku</a>
%e A109741 a(2) = 2:
%e A109741 12|34 12|34
%e A109741 34|12 34|12
%e A109741 --+-- --+--
%e A109741 21|43 23|41
%e A109741 43|21 41|23
%Y A109741 Sequence in context: A034251 A051241 A094486 this_sequence A105759 A154422 
               A154423
%Y A109741 Adjacent sequences: A109738 A109739 A109740 this_sequence A109742 A109743 
               A109744
%K A109741 nonn
%O A109741 0,3
%A A109741 N. J. A. Sloane (njas(AT)research.att.com), Aug 13 2005