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) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 5 |
| 7 | 63 |
| 8 | 476 |
| 9 | 2772 |
| 10 | 13680 |
| 11 | 60060 |
| 12 | 241472 |
| 13 | 906048 |
| 14 | 3214848 |
| 15 | 10890880 |
| 16 | 35481600 |
| 17 | 111794176 |
| 18 | 342171648 |
| 19 | 1021031424 |
| 20 | 2979102720 |
| 21 | 8520171520 |
| 22 | 23934468096 |
| 23 | 66156625920 |
| 24 | 180198047744 |
| 25 | 484304486400 |
| 26 | 1285790105600 |
| 27 | 3375480176640 |
| 28 | 8769899593728 |
| 29 | 22567515586560 |
| 30 | 57557594931200 |