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 | 1 |
| 1 | 0 |
| 2 | 240 |
| 3 | 13440 |
| 4 | 1260720 |
| 5 | 137813760 |
| 6 | 17141798400 |
| 7 | 2336327078400 |
| 8 | 341350907713200 |