Dear participants, processing of the square # 21 is fully completed! The square:

0 1 2 3 4 5 6 7 8 9 A B
1 2 0 4 5 3 8 6 7 B 9 A
3 4 5 1 2 0 B 9 A 6 7 8
8 7 6 A 9 B 0 2 1 5 4 3
7 6 8 9 B A 1 0 2 3 5 4
A 9 B 7 6 8 3 5 4 0 2 1
5 3 4 0 1 2 9 A B 7 8 6
B A 9 8 7 6 5 4 3 2 1 0
2 0 1 5 3 4 7 8 6 A B 9
9 B A 6 8 7 4 3 5 1 0 2
6 8 7 B A 9 2 1 0 4 3 5
4 5 3 2 0 1 A B 9 8 6 7

has 1185453085 orthogonal mates, like square square # 8. Presumably a some unknown transformations exist that can convert a square of other main class to this square.

Thank you for project attention, support and donation of CPU time!