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 | 4 |
| 5 | 6 |
| 6 | 60 |
| 7 | 60 |
| 8 | 120 |
| 9 | 144 |
| 10 | 7920 |
| 11 | 55440 |
| 12 | 18480 |
| 13 | 7920 |
| 14 | 27720 |
| 15 | 2520 |
| 16 | 637560 |
| 17 | 8288280 |
| 18 | 480720240 |
| 19 | 480720240 |
| 20 | 480720240 |
| 21 | 480720240 |
| 22 | 480720240 |
| 23 | 1442160720 |
| 24 | 9854764920 |
| 25 | 59128589520 |
| 26 | 59128589520 |
| 27 | 147821473800 |
| 28 | 670124014560 |