A058170 - OEIS

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).

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: A369595 A220621 A360587 * A238206 A127896 A010757

Adjacent sequences: A058167 A058168 A058169 * A058171 A058172 A058173

KEYWORD

nonn,tabl,hard

AUTHOR

Christian G. Bower, Nov 19 2000

STATUS

approved

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