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 | 1 |
| 2 | 0 |
| 3 | -6 |
| 4 | 60 |
| 5 | -600 |
| 6 | 5880 |
| 7 | -38640 |
| 8 | -624960 |
| 9 | 45077760 |
| 10 | -1773129600 |
| 11 | 58531809600 |
| 12 | -1657462435200 |
| 13 | 33703750080000 |
| 14 | 171919752076800 |
| 15 | -76383384045696000 |
| 16 | 6034124486347776000 |
| 17 | -348318907415331840000 |
| 18 | 15862493882862941184000 |