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 | 2 |
| 5 | 2 |
| 6 | 36 |
| 7 | 36 |
| 8 | 144 |
| 9 | 144 |
| 10 | 1440 |
| 11 | 1440 |
| 12 | 17280 |
| 13 | 17280 |
| 14 | 241920 |
| 15 | 3628800 |
| 16 | 29030400 |
| 17 | 29030400 |
| 18 | 1567641600 |
| 19 | 1567641600 |
| 20 | 156764160000 |
| 21 | 9876142080000 |
| 22 | 217275125760000 |
| 23 | 217275125760000 |
| 24 | 1738201006080000 |
| 25 | 1738201006080000 |