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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058170 Triangle: Number of asymmetric semigroups of order n with k idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator). 0
1, 2, 1, 3, 7, 2, 10, 28, 33, 7, 82, 153, 261, 213, 37, 2511, 1227, 2266, 2989, 1709, 263, 600106, 26033, 24176, 39176, 38346, 16306, 2134 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..28.

Index entries for sequences related to semigroups

EXAMPLE

1; 2,1; 3,7,2; 10,28,33,7; 82,153,261,213,37; ...

CROSSREFS

Row sums give A058107.

Sequence in context: A116381 A176120 A220621 * A238206 A127896 A010757

Adjacent sequences:  A058167 A058168 A058169 * A058171 A058172 A058173

KEYWORD

nonn,tabl,hard

AUTHOR

Christian G. Bower, Nov 19 2000

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 10:27 EDT 2018. Contains 316353 sequences. (Running on oeis4.)