A058170 - cp's OEIS frontend

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).

n	a(n)
1	1
2	2
3	1
4	3
5	7
6	2
7	10
8	28
9	33
10	7
11	82
12	153
13	261
14	213
15	37
16	2511
17	1227
18	2266
19	2989
20	1709
21	263
22	600106
23	26033
24	24176
25	39176
26	38346
27	16306
28	2134

[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]