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) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 60 |
| 4 | 420 |
| 5 | 1260 |
| 6 | 13860 |
| 7 | 360360 |
| 8 | 360360 |
| 9 | 6126120 |
| 10 | 116396280 |
| 11 | 116396280 |
| 12 | 2677114440 |
| 13 | 13385572200 |
| 14 | 40156716600 |
| 15 | 2329089562800 |
| 16 | 72201776446800 |
| 17 | 72201776446800 |
| 18 | 72201776446800 |
| 19 | 2671465728531600 |
| 20 | 2671465728531600 |