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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

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 July 30 07:13 EDT 2014. Contains 245054 sequences.