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 | 4 |
| 3 | 48 |
| 4 | 1 |
| 5 | 3840 |
| 6 | 92160 |
| 7 | 645120 |
| 8 | 3440640 |
| 9 | 30965760 |
| 10 | 14863564800 |
| 11 | 24222105600 |
| 12 | 7847962214400 |
| 13 | 40809403514880 |
| 14 | 5713316492083200 |
| 15 | 7617755322777600 |
| 16 | 5484783832399872000 |
| 17 | 5328075722902732800 |
| 18 | 1220613711064989696000 |