A258719 Number of self-dual noncommutative groupoids with n elements.

0, 0, 9, 16192, 198862625, 42002510818752, 207278622607612079818, 29215384735442091573649485568, 137562588659577384442574662095693261747, 24724406349174154904254665510689036571978910174560

Offset: 1

Author

N. J. A. Sloane, Jun 18 2015

Keywords

• nonn
• more

Links

• N. J. A. Sloane, Overview of A001329, A001423-A001428, A258719, A258720.
• T. Tamura, Some contributions of computation to semigroups and groupoids, pp. 229-261 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970. (Annotated and scanned copy)

Crossrefs

Cf. A029850, A001425, A258720.

Formula

a(n) = A029850(n) - A001425(n). - Andrew Howroyd, May 06 2023

Extensions

a(5)-a(10) from Andrew Howroyd, May 06 2023