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 | 4 |
| 4 | 24 |
| 5 | 240 |
| 6 | 4320 |
| 7 | 146880 |
| 8 | 9694080 |
| 9 | 1260230400 |
| 10 | 325139443200 |
| 11 | 167121673804800 |
| 12 | 171466837323724800 |
| 13 | 351507016513635840000 |
| 14 | 1440475753672879672320000 |
| 15 | 11803258325595576034990080000 |