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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 6 |
| 7 | 30 |
| 8 | 120 |
| 9 | 720 |
| 10 | 4320 |
| 11 | 38880 |
| 12 | 233280 |
| 13 | 2566080 |
| 14 | 25660800 |
| 15 | 282268800 |
| 16 | 3104956800 |
| 17 | 46574352000 |
| 18 | 558892224000 |
| 19 | 9501167808000 |
| 20 | 133016349312000 |
| 21 | 2261277938304000 |
| 22 | 40703002889472000 |
| 23 | 854763060678912000 |
| 24 | 13676208970862592000 |
| 25 | 300876597358977024000 |