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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 48 |
| 5 | 1440 |
| 6 | 0 |
| 7 | 19353600 |
| 8 | 4180377600 |
| 9 | 25070769561600 |
| 10 | 3200285563453440000 |