A038020 Triangle: T(n,k), k<=n: groupoids with a nontrivial symmetry with n elements and k idempotents.
0, 0, 0, 2, 0, 2, 9, 54, 0, 30, 15376, 12664, 14304, 4096, 3187
Offset: 0
Examples
Triangle begins:
0;
0, 0;
2, 0, 2;
9, 54, 0, 30;
15376, 12664, 14304, 4096, 3187;
...