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 | 1 |
| 3 | 5 |
| 4 | 42 |
| 5 | 55440 |
| 6 | 1235520 |
| 7 | 8821612800 |
| 8 | 335221286400 |
| 9 | 7124122778572800 |
| 10 | 221504779785446277120000 |
| 11 | 17166620433372086476800000 |
| 12 | 2210327142511928825790332928000000 |