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 | 2 |
| 3 | 6 |
| 4 | 48 |
| 5 | 360 |
| 6 | 3600 |
| 7 | 40320 |
| 8 | 524160 |
| 9 | 7620480 |
| 10 | 123379200 |
| 11 | 2195424000 |
| 12 | 42631142400 |
| 13 | 896690995200 |
| 14 | 20312541849600 |
| 15 | 492993236736000 |
| 16 | 12762901831680000 |
| 17 | 351063491530752000 |
| 18 | 10224590808047616000 |