A266167 Number of isotopism classes of unordered pairs of orthogonal Latin squares.

1, 0, 1, 1, 2, 0, 20, 23362, 1101734942

Offset

1,5

Comments

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.

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.

Links

Table of n, a(n) for n=1..9.

J. Egan and I. M. Wanless, Enumeration of MOLS of small order, Mathematics of Computation 85, 2016, 799-824.

Ian Wanless, Data on MOLS

Crossrefs

Cf. A072377, A129732, A266166, A266168, A266169.

Sequence in context: A182661 A189772 A217311 * A290465 A256303 A156438

Adjacent sequences: A266164 A266165 A266166 * A266168 A266169 A266170

Keyword

nonn,more

Author

Ian Wanless, Dec 22 2015

Status

approved