login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058129 Number of monoids (semigroups with identity) of order n. 12
0, 1, 2, 7, 35, 228, 2237, 31559, 1668997 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..8.

Eric Postpischil, Posting to sci.math newsgroup, May 21 1990

Index entries for sequences related to monoids

FORMULA

a(n) = 2*A058133(n) - A058132(n).

a(n) < A027851(n) except for equality iff n = 1. - M. F. Hasler, Dec 10 2018

CROSSREFS

Cf. A058132, A058133.

Cf. A027851 (number of all nonisomorphic semigroups).

Sequence in context: A014307 A000154 A003713 * A101514 A247240 A266356

Adjacent sequences:  A058126 A058127 A058128 * A058130 A058131 A058132

KEYWORD

nonn,hard,more

AUTHOR

Christian G. Bower, Nov 13 2000

EXTENSIONS

a(8) from Christian G. Bower, Dec 26 2006

a(0) = 0 prepended by M. F. Hasler, Dec 10 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 20 07:56 EST 2019. Contains 319325 sequences. (Running on oeis4.)