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 | 1 |
| 2 | 84 |
| 3 | 1397520 |
| 4 | 5314794912000 |
| 5 | 4855173934730716800000 |
| 6 | 1090093558153665322315192780800000 |
| 7 | 60907190511553979457004412118419080463155200000 |