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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 840 |
| 7 | 6720 |
| 8 | 60480 |
| 9 | 665280 |
| 10 | 8648640 |
| 11 | 147026880 |
| 12 | 2793510720 |
| 13 | 64250746560 |
| 14 | 1606268664000 |
| 15 | 43369253928000 |
| 16 | 1257708363912000 |
| 17 | 38988959281272000 |
| 18 | 1247646697000704000 |
| 19 | 46162927789026048000 |
| 20 | 1892680039350067968000 |
| 21 | 81385241692052922624000 |
| 22 | 3825106359526487363328000 |