A181770 Number of isomorphism classes of racks of order n.

1, 1, 2, 6, 19, 74, 353, 2080, 16023, 159526, 2093244, 36265070, 836395102, 25794670618

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Přemysl Jedlička, Agata Pilitowska, Anna Zamojska-Dzienio, Multipermutation set theoretic solutions of the Yang-Baxter equation of level 2, arXiv:1901.01471 [math.QA], 2019.

Sam Nelson, Quandles and Racks

Petr Vojtěchovský and Seung Yeop Yang, Enumeration of racks and quandles up to isomorphism, Mathematics of Computation, 88 (2019), 2523-2540; arXiv:1911.04991 [math.QA], 2019.

Crossrefs

Cf. A181769.

Sequence in context: A150119 A361489 A268569 * A138800 A008989 A057240

Adjacent sequences: A181767 A181768 A181769 * A181771 A181772 A181773

Keyword

nonn,hard,more

Author

James McCarron

Extensions

a(9)-a(13) from Petr Vojtěchovský and Seung Yeop Yang added by Andrey Zabolotskiy, Jun 15 2022

Status

approved