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On the Number of Latin Squares
Brendan D. McKay and Ian M. Wanless
Department of Computer Science, Australian National University, Canberra, ACT 0200, Australia
{bdm, imw}@cs.anu.edu.au
Annals of Combinatorics 9 (3) p.335-344 September, 2005
AMS Subject Classification: 05B15, 05C70, 15A15
We (1) determine the number of Latin rectangles with 11 columns and each possible number of rows, including the Latin squares of order 11, (2) answer some questions of Alter by showing that the number of reduced Latin squares of order n is divisible by f ! where f is a particular integer close to , (3) provide a formula for the number of Latin squares in terms of permanents of
(+1,-1)-matrices, (4) find the extremal values for the number of 1-factorisations of k-regular bipartite graphs on 2n vertices whenever , (5) show that the proportion of Latin squares with a non-trivial symmetry group tends quickly to zero as the order increases.
Keywords: Latin square, enumeration, 1-factorisation, permanent, regular bipartite graph


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