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) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | -432000 |
| 7 | 1 |
| 8 | -3456000 |
| 9 | -9504000 |
| 10 | -209520000 |
| 11 | -389664000 |
| 12 | -5952960000 |
| 13 | -289595177265600 |