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 | 3 |
| 5 | 3 |
| 6 | 5 |
| 7 | 45 |
| 8 | 315 |
| 9 | 35 |
| 10 | 567 |
| 11 | 14175 |
| 12 | 51975 |
| 13 | 467775 |
| 14 | 868725 |
| 15 | 2837835 |
| 16 | 638512875 |
| 17 | 638512875 |
| 18 | 1206079875 |
| 19 | 97692469875 |
| 20 | 371231385525 |
| 21 | 441942125625 |
| 22 | 17717861581875 |
| 23 | 2143861251406875 |
| 24 | 16436269594119375 |
| 25 | 5917057053882975 |
| 26 | 284473896821296875 |
| 27 | 1780595872696265625 |