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) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 4 |
| 6 | 20 |
| 7 | 20 |
| 8 | 240 |
| 9 | 1440 |
| 10 | 10080 |
| 11 | 10080 |
| 12 | 161280 |
| 13 | 161280 |
| 14 | 1451520 |
| 15 | 11612160 |
| 16 | 371589120 |
| 17 | 371589120 |
| 18 | 7803371520 |
| 19 | 7803371520 |
| 20 | 187280916480 |
| 21 | 1872809164800 |
| 22 | 24346519142400 |
| 23 | 24346519142400 |
| 24 | 1071246842265600 |
| 25 | 10712468422656000 |