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.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 252 |
| 3 | 15288 |
| 4 | 1089270 |
| 5 | 84963060 |
| 6 | 7023612960 |
| 7 | 604604070720 |
| 8 | 53620823521980 |
| 9 | 4865593245513000 |
| 10 | 449580815885401200 |
| 11 | 42156561463105471200 |
| 12 | 4001360292206427641400 |
| 13 | 383704407665664889683600 |