OFFSET
2,2
COMMENTS
From James East, Jul 13 2016: (Start)
a(5) and a(6) were calculated by James Mitchell using the GAP System Packages Semigroups (see link).
a(n) is also the number of minimal size all-idempotent generating sets for the singular part of the Brauer monoid (see East-Gray paper). (End)
LINKS
J. East, R. D. Gray, Diagram monoids and Graham-Houghton graphs: idempotents and generating sets of ideals, arXiv:1404.2359 [math.GR], 2014.
GAP, Semigroups
Ronald Niles, C++ project on GitHub
Ronald Niles, Computation of A244493
PROG
(C++) See Niles link.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Jul 05 2014
EXTENSIONS
Name clarified by James East, Jul 14 2016
a(6) corrected and a(7) added by Ronald Niles, Apr 21 2017
a(8) added by Ronald Niles, Jun 25 2017
STATUS
approved