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 | 6 |
| 2 | 84 |
| 3 | 2016 |
| 4 | 72576 |
| 5 | 3628800 |
| 6 | 239500800 |
| 7 | 20118067200 |
| 8 | 2092278988800 |
| 9 | 263627152588800 |
| 10 | 39544072888320000 |
| 11 | 6959756828344320000 |
| 12 | 1419790392982241280000 |
| 13 | 332230951957844459520000 |
| 14 | 88373433220786626232320000 |
| 15 | 26512029966235987869696000000 |