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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 36960 |
| 9 | 302400 |
| 10 | 2761920 |
| 11 | 27941760 |
| 12 | 310495680 |
| 13 | 3760922880 |
| 14 | 49324923648 |
| 15 | 696388492800 |
| 16 | 10530709862400 |
| 17 | 169811234611200 |
| 18 | 2908629247795200 |
| 19 | 52738216760033280 |
| 20 | 1009115747652096000 |