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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 12 |
| 5 | 60 |
| 6 | 540 |
| 7 | 0 |
| 8 | 20160 |
| 9 | 181440 |
| 10 | 907200 |
| 11 | 19958400 |
| 12 | 359251200 |
| 13 | 1556755200 |
| 14 | 32691859200 |
| 15 | 0 |
| 16 | 10461394944000 |
| 17 | 177843714048000 |
| 18 | 1600593426432000 |
| 19 | 60822550204416000 |
| 20 | 608225502044160000 |
| 21 | 38318206628782080000 |
| 22 | 702500454861004800000 |
| 23 | 12926008369442488320000 |