A350017 Number of isotopism classes containing symmetric unipotent reduced Latin squares of order 2n.

1, 1, 1, 6, 396, 526915616, 1132835421602062347

Offset

1,4

Comments

Isotopism classes are obtained by permuting rows, permuting columns and permuting symbols. There is a stronger notion of equivalence called "species" (also known as main classes and paratopism classes). For this particular problem the counts for species equal the counts for isotopism classes.

Links

Table of n, a(n) for n=1..7.

Brendan D. McKay and Ian M. Wanless, Enumeration of Latin squares with conjugate symmetry, J. Combin. Des. 30 (2022), 105-130.

Crossrefs

For odd n the terms equal A000474.

Cf. A350009.

Sequence in context: A306887 A289894 A058807 * A000474 A291593 A029591

Adjacent sequences: A350014 A350015 A350016 * A350018 A350019 A350020

Keyword

nonn,more

Author

Ian Wanless, Dec 08 2021

Status

approved