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 | 4 |
| 3 | 12 |
| 4 | 60 |
| 5 | 240 |
| 6 | 1860 |
| 7 | 10080 |
| 8 | 95760 |
| 9 | 766080 |
| 10 | 8210160 |
| 11 | 79833600 |
| 12 | 1100484000 |
| 13 | 12454041600 |
| 14 | 188172784800 |
| 15 | 2683799838720 |
| 16 | 44951306400000 |
| 17 | 711374856192000 |
| 18 | 13745322470880000 |
| 19 | 243290200817664000 |
| 20 | 5142812718440517120 |
| 21 | 103294640229580800000 |
| 22 | 2351280996859354560000 |