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 | 2 |
| 3 | 12 |
| 4 | 24 |
| 5 | 720 |
| 6 | 720 |
| 7 | 151200 |
| 8 | 302400 |
| 9 | 1814400 |
| 10 | 1814400 |
| 11 | 4191264000 |
| 12 | 4191264000 |
| 13 | 125863657920000 |
| 14 | 125863657920000 |
| 15 | 125863657920000 |
| 16 | 251727315840000 |
| 17 | 128509312009478400000 |
| 18 | 128509312009478400000 |
| 19 | 1246500488605217541696000000 |