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 | 2 |
| 3 | 12 |
| 4 | 12 |
| 5 | 1120 |
| 6 | 3360 |
| 7 | 6720 |
| 8 | 6720 |
| 9 | 172972800 |
| 10 | 1210809600 |
| 11 | 7264857600 |
| 12 | 36324288000 |
| 13 | 145297152000 |
| 14 | 435891456000 |
| 15 | 871782912000 |
| 16 | 871782912000 |
| 17 | 1676837160768946176000 |
| 18 | 25152557411534192640000 |
| 19 | 352135803761478696960000 |
| 20 | 4577765448899223060480000 |