|
Search: id:A058133
|
|
|
| A058133 |
|
Number of monoids (semigroups with identity) of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator). |
|
+0
7
|
|
| 1, 2, 6, 27, 156, 1373, 17730, 858977, 1844075697, 52991253973742
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
REFERENCES
|
Andreas Distler and Tom Kelsey, The Monoids of Order Eight and Nine, in Intelligent Computer Mathematics, Lecture Notes in Computer Science, Volume 5144/2008, Springer-Verlag. [From N. J. A. Sloane, Jul 10 2009]
|
|
LINKS
|
Eric Postpischil Posting to sci.math newsgroup, May 21 1990
Index entries for sequences related to monoids
A Distler, T Kelsey. The Monoids of Orders Eight, Nine & Ten. preprint. [From Max Alekseyev (maxale(AT)gmail.com), Jul 13 2009]
|
|
CROSSREFS
|
a(n)=(A058129(n)+A058132(n))/2.
Cf. A001423, A151823.
Sequence in context: A030858 A030932 A118192 this_sequence A009308 A032186 A122938
Adjacent sequences: A058130 A058131 A058132 this_sequence A058134 A058135 A058136
|
|
KEYWORD
|
nonn,more,hard
|
|
AUTHOR
|
Christian G. Bower (bowerc(AT)usa.net), Nov 13 2000
|
|
EXTENSIONS
|
a(8) and a(9) from the Distler-Kelsey paper [N. J. A. Sloane, Jul 10 2009]
a(10) from the Distler-Kelsey preprint. Max Alekseyev (maxale(AT)gmail.com), Jul 13 2009
|
|
|
Search completed in 0.003 seconds
|
