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 | 120 |
| 6 | 1440 |
| 7 | 10920 |
| 8 | 67200 |
| 9 | 367416 |
| 10 | 1864800 |
| 11 | 9003720 |
| 12 | 41976000 |
| 13 | 190788312 |
| 14 | 850930080 |
| 15 | 3741028200 |
| 16 | 16264684800 |
| 17 | 70093951608 |
| 18 | 299953709280 |
| 19 | 1276255985160 |
| 20 | 5404640136000 |
| 21 | 22796986414104 |
| 22 | 95836788986400 |
| 23 | 401733800351400 |
| 24 | 1679813323056000 |