A030249 Number of nonisomorphic idempotent groupoids with a nontrivial symmetry.
0, 0, 2, 30, 3187
Offset: 0
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Triangle begins:
0;
0, 0;
2, 0, 2;
9, 54, 0, 30;
15376, 12664, 14304, 4096, 3187;
...