OFFSET
2,1
COMMENTS
We regard two grids as inequivalent if one cannot be transformed into another by some sequence of symmetries, or by relabeling. For the 2 X 3 Sudoku grids case the allowed equivalences are (see link to Jarvis):
- relabeling entries; reflection; rotation;
- permutation of blocks of columns 1-2, 3-4 and 5-6;
- permutation of blocks of rows 1-3 and 4-6;
- permutation of columns 1-2;
- permutation of columns 3-4;
- permutation of columns 5-6;
- permutation of rows 1-3;
- permutation of rows 4-6.
LINKS
Frazer Jarvis, Sudoku enumeration problems
Jordy Vanpoucke, Mutually orthogonal latin squares and their generalizations
EXAMPLE
a(2) = 2:
.
12|34 12|34
34|12 34|12
--+-- --+--
21|43 23|41
43|21 41|23
.
An example of 2 X 3 Sudoku grids:
.
14|25|36
35|16|24
26|34|15
--+--+--
41|52|63
52|63|41
63|41|52
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Aug 19 2017
STATUS
approved