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 | 1 |
| 3 | 2 |
| 4 | 24 |
| 5 | 1344 |
| 6 | 1128960 |
| 7 | 12198297600 |
| 8 | 2697818265354240 |
| 9 | 15224734061278915461120 |
| 10 | 2750892211809148994633229926400 |
| 11 | 19464657391668924966616671344752852992000 |