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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 4320 |
| 8 | 29520 |
| 9 | 225360 |
| 10 | 1890720 |
| 11 | 17169120 |
| 12 | 166112640 |
| 13 | 1680462720 |
| 14 | 18189031680 |
| 15 | 209008512000 |
| 16 | 2532028896000 |
| 17 | 32143053484800 |
| 18 | 425585741760000 |
| 19 | 5865854258188800 |
| 20 | 84489178710067200 |
| 21 | 1266667808011315200 |
| 22 | 19700712491727974400 |