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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 0 |
| 6 | 0 |
| 7 | 2520 |
| 8 | 20160 |
| 9 | 0 |
| 10 | 1209600 |
| 11 | 19958400 |
| 12 | 79833600 |
| 13 | 1556755200 |
| 14 | 39956716800 |
| 15 | 326918592000 |
| 16 | 5056340889600 |
| 17 | 148203095040000 |
| 18 | 1867358997504000 |
| 19 | 30411275102208000 |
| 20 | 946128558735360000 |
| 21 | 15965919428659200000 |
| 22 | 293266062902292480000 |