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 | 1 |
| 3 | 3 |
| 4 | 1 |
| 5 | 15 |
| 6 | 45 |
| 7 | 105 |
| 8 | 315 |
| 9 | 405 |
| 10 | 4725 |
| 11 | 155925 |
| 12 | 467775 |
| 13 | 96525 |
| 14 | 42567525 |
| 15 | 638512875 |
| 16 | 30405375 |
| 17 | 10854718875 |
| 18 | 97692469875 |
| 19 | 618718975875 |
| 20 | 189403768125 |
| 21 | 194896477400625 |
| 22 | 238206805711875 |
| 23 | 7044115540336875 |
| 24 | 8701554491004375 |