A211172 A Sudoku torus.

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

Offset

1,1

Comments

The sequence is a listing for a Sudoku grid:

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 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 5 2 4 3

4 3 2 9 1 8 7 6 5

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'.

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

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

Links

Table of n, a(n) for n=1..81.

Mathworld, Sudoku

Wikipedia, Sudoku

Example

If a puzzle has say:
   |x
  5|
___|x
then x cannot be 5.

Crossrefs

Cf. A107739.

Cf. A114288, A112454 (lexicographic grids).

Sequence in context: A195786 A201330 A089826 * A152149 A338287 A379334

Adjacent sequences: A211169 A211170 A211171 * A211173 A211174 A211175

Keyword

nonn,fini,full,tabf

Author

Jon Perry, Jan 31 2013

Status

approved