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 | 16 |
| 3 | 0 |
| 4 | 720 |
| 5 | 0 |
| 6 | 50560 |
| 7 | 0 |
| 8 | 4649680 |
| 9 | 0 |
| 10 | 514031616 |
| 11 | 0 |
| 12 | 64941883776 |
| 13 | 0 |
| 14 | 9071319628800 |
| 15 | 0 |
| 16 | 1369263687414480 |
| 17 | 0 |
| 18 | 219705672931613440 |
| 19 | 0 |
| 20 | 37024402443528248320 |
| 21 | 0 |
| 22 | 6493814173413849784320 |
| 23 | 0 |
| 24 | 1177304833671218302960000 |
| 25 | 0 |
| 26 | 219456611569479963675136000 |
| 27 | 0 |