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 | 4 |
| 3 | 4320 |
| 4 | 11496038400 |
| 5 | 291948240981196800000 |
| 6 | 190982059064777562218142105600000000 |
| 7 | 7081230833474514688657438735472338312479375360000000000 |