A211172 - OEIS

%I #14 Feb 16 2013 18:30:21

%S 6,5,7,3,4,2,1,9,8,9,8,1,5,6,7,4,3,2,3,2,4,8,9,1,6,5,7,5,7,6,2,3,4,9,

%T 8,1,8,1,9,7,5,6,3,2,4,2,4,3,1,8,9,5,7,6,7,6,5,4,2,3,8,1,9,1,9,8,6,7,

%U 5,2,4,3,4,3,2,9,1,8,7,6,5

%N A Sudoku torus.

%C The sequence is a listing for a Sudoku grid:

%C 6 5 7 3 4 2 1 9 8

%C 9 8 1 5 6 7 4 3 2

%C 3 2 4 8 9 1 6 5 7

%C 5 7 6 2 3 4 9 8 1

%C 8 1 9 7 5 6 3 2 4

%C 2 4 3 1 8 9 5 7 6

%C 7 6 5 4 2 3 8 1 9

%C 1 9 8 6 7 5 2 4 3

%C 4 3 2 9 1 8 7 6 5

%C No two diagonally adjacent elements are the same. If the grid is rolled into a cylinder either way, this is still true making a 'Sudoku torus'.

%C This extra information can be used to construct puzzles that use 'no diagonal' logic.

%C The two lexicographical Sudoki in the cross-references have one internal diagonal each and several external diagonals.

%H Mathworld, <a href="http://mathworld.wolfram.com/Sudoku.html">Sudoku</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Sudoku">Sudoku</a>

%e If a puzzle has say:

%e    |x

%e   5|

%e ___|x

%e then x cannot be 5.

%Y Cf. A107739.

%Y Cf. A114288, A112454 (lexicographic grids).

%K nonn,fini,full,tabf

%O 1,1

%A _Jon Perry_, Jan 31 2013