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 | 0 |
| 1 | 2 |
| 2 | 24 |
| 3 | 180 |
| 4 | 1120 |
| 5 | 6300 |
| 6 | 33264 |
| 7 | 168168 |
| 8 | 823680 |
| 9 | 3938220 |
| 10 | 18475600 |
| 11 | 85357272 |
| 12 | 389398464 |
| 13 | 1757701400 |
| 14 | 7862853600 |
| 15 | 34901442000 |
| 16 | 153876579840 |
| 17 | 674412197580 |
| 18 | 2940343837200 |
| 19 | 12759640231800 |
| 20 | 55138611528000 |
| 21 | 237371722628040 |
| 22 | 1018383898440480 |