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) |
|---|---|
| 4 | 1152 |
| 5 | 172800 |
| 6 | 0 |
| 7 | 12192768000 |
| 8 | 608662978560000 |
| 9 | 464573723443200000 |
| 10 | 0 |