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

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

Offset

1,3

Links

Table of n, a(n) for n=1..10.

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)

Formula

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

Crossrefs

Cf. A029850, A001425, A258720.

Sequence in context: A069501 A360762 A206461 * A292562 A140596 A280900

Adjacent sequences: A258716 A258717 A258718 * A258720 A258721 A258722

Keyword

nonn,more

Author

N. J. A. Sloane, Jun 18 2015

Extensions

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

Status

approved