A058118 Triangle: self-converse semigroups of order n with k idempotents.

1, 2, 1, 5, 5, 2, 18, 24, 16, 6, 93, 123, 112, 58, 19, 930, 754, 764, 542, 254, 68, 22899, 6721, 5567, 4751, 2933, 1214, 285, 1937266, 123988, 49969, 41939, 31392, 17396, 6513, 1376, 613365656, 8265721, 739317, 410158, 328937, 223226, 113160, 38979, 7510

Offset

1,2

Links

Table of n, a(n) for n=1..45.

Andreas Distler, Classification and Enumeration of Finite Semigroups, A Thesis Submitted for the Degree of PhD, University of St Andrews (2010).

Index entries for sequences related to semigroups

Example

1; 2,1; 5,5,2; 18,24,16,6; 93,123,112,58,19; ...

Crossrefs

Row sums give A029851. Main diagonal: A058122. Columns 1-3: A058119-A058121.

Sequence in context: A118244 A108410 A058116 * A332632 A124226 A248797

Adjacent sequences: A058115 A058116 A058117 * A058119 A058120 A058121

Keyword

nonn,tabl,hard

Author

Christian G. Bower, Nov 10 2000

Extensions

More terms from Andreas Distler, Jan 13 2011

Status

approved