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 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 120 |
| 5 | 1920 |
| 6 | 40320 |
| 7 | 1028160 |
| 8 | 30965760 |
| 9 | 1077753600 |
| 10 | 42551308800 |
| 11 | 1878484608000 |
| 12 | 91686654259200 |
| 13 | 4902558383923200 |
| 14 | 284994551761920000 |
| 15 | 17895345882365952000 |
| 16 | 1207064057173438464000 |
| 17 | 87041570211234422784000 |