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 | 2 |
| 4 | 6 |
| 5 | 12 |
| 6 | 60 |
| 7 | 30 |
| 8 | 210 |
| 9 | 840 |
| 10 | 2520 |
| 11 | 1260 |
| 12 | 13860 |
| 13 | 13860 |
| 14 | 180180 |
| 15 | 90090 |
| 16 | 30030 |
| 17 | 240240 |
| 18 | 4084080 |
| 19 | 6126120 |
| 20 | 116396280 |
| 21 | 58198140 |
| 22 | 58198140 |