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) |
|---|---|
| 5 | 0 |
| 6 | 20 |
| 7 | 360 |
| 8 | 5922 |
| 9 | 82880 |
| 10 | 1017060 |
| 11 | 11165280 |
| 12 | 123760560 |
| 13 | 1310267904 |
| 14 | 14197154400 |
| 15 | 153775564800 |
| 16 | 1646888944800 |
| 17 | 18660402342400 |
| 18 | 201542310930240 |
| 19 | 2419644394552320 |
| 20 | 26818494698361600 |
| 21 | 342175409500446720 |
| 22 | 3913572812111424000 |
| 23 | 53353484649907200000 |