A058118 - OEIS

%I #8 Mar 31 2012 10:23:58

%S 1,2,1,5,5,2,18,24,16,6,93,123,112,58,19,930,754,764,542,254,68,22899,

%T 6721,5567,4751,2933,1214,285,1937266,123988,49969,41939,31392,17396,

%U 6513,1376,613365656,8265721,739317,410158,328937,223226,113160,38979,7510

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

%H Andreas Distler, <a href="http://hdl.handle.net/10023/945">Classification and Enumeration of Finite Semigroups</a>, A Thesis Submitted for the Degree of PhD, University of St Andrews (2010).

%H <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a>

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

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

%K nonn,tabl,hard

%O 1,2

%A _Christian G. Bower_, Nov 10 2000

%E More terms from _Andreas Distler_, Jan 13 2011