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%I #20 Dec 10 2021 11:08:36
%S 1,0,1,1,2,0,20,23362,1101734942
%N Number of isotopism classes of unordered pairs of orthogonal Latin squares.
%C The following operations produce things that are counted as equivalent: simultaneous permutation of the rows or columns of both squares; permutation of the symbols within either square; interchanging the squares.
%C This sequence is also the number of trisotopism classes of *ordered* pairs of orthogonal Latin squares, where the following operations produce things that are counted as equivalent: simultaneous permutation of the rows or columns of both squares; permutation of the symbols within either square; transposing both squares.
%H J. Egan and I. M. Wanless, <a href="http://dx.doi.org/10.1090/mcom/3010">Enumeration of MOLS of small order</a>, Mathematics of Computation 85, 2016, 799-824.
%H Ian Wanless, <a href="http://users.monash.edu.au/~iwanless/data/MOLS/">Data on MOLS</a>
%Y Cf. A072377, A129732, A266166, A266168, A266169.
%K nonn,more
%O 1,5
%A _Ian Wanless_, Dec 22 2015