OFFSET
1,2
COMMENTS
An m X m Latin square consists of m sets of the numbers 1 to m arranged in such a way that no row or column contains the same number twice.
Two m X m Latin squares are orthogonal if no pair of corresponding elements occurs more than once.
A self-orthogonal Latin square is a Latin square that is orthogonal to its transpose.
There are 19353600 self-orthogonal Latin squares of order 7.
LINKS
Colin Barker, Table of n, a(n) for n = 1..500
Eric Weisstein's World of Mathematics, Latin square
Wikipedia, Latin square
EXAMPLE
The first four squares are:
1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7
3 4 2 5 6 7 1 3 4 2 5 6 7 1 3 4 2 5 6 7 1 3 4 2 5 6 7 1
4 7 6 3 1 2 5 5 1 6 7 3 4 2 5 7 6 1 3 2 4 5 7 6 1 3 2 4
6 1 5 7 2 4 3 6 7 1 3 2 5 4 6 1 7 2 4 3 5 6 1 7 3 2 4 5
2 5 7 6 3 1 4 2 5 4 6 7 1 3 2 5 1 3 7 4 6 2 5 4 6 7 1 3
7 3 1 2 4 5 6 7 3 5 1 4 2 6 7 3 4 6 1 5 2 7 3 1 2 4 5 6
5 6 4 1 7 3 2 4 6 7 2 1 3 5 4 6 5 7 2 1 3 4 6 5 7 1 3 2
CROSSREFS
KEYWORD
nonn,fini,tabf
AUTHOR
Colin Barker, Dec 16 2016
STATUS
approved