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 | -1 |
| 2 | 3 |
| 3 | -45 |
| 4 | 315 |
| 5 | -14175 |
| 6 | 467775 |
| 7 | -42567525 |
| 8 | 638512875 |
| 9 | -97692469875 |
| 10 | 9280784638125 |
| 11 | -2143861251406875 |
| 12 | 147926426347074375 |
| 13 | -48076088562799171875 |
| 14 | 9086380738369043484375 |
| 15 | -3952575621190533915703125 |