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

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058117 Number of commutative semigroups of order n with 1 idempotent. 1
1, 2, 5, 16, 62, 342, 3435 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..7.

Index entries for sequences related to semigroups

CROSSREFS

Column 1 of A058116.

Sequence in context: A144188 A157314 A159603 * A007124 A112951 A124470

Adjacent sequences:  A058114 A058115 A058116 * A058118 A058119 A058120

KEYWORD

nonn,hard

AUTHOR

Christian G. Bower, Nov 09 2000

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified December 20 04:40 EST 2014. Contains 252241 sequences.