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 | -3 |
| 2 | 12 |
| 3 | -67 |
| 4 | 495 |
| 5 | -4596 |
| 6 | 51583 |
| 7 | -680037 |
| 8 | 10306152 |
| 9 | -176591665 |
| 10 | 3376207461 |
| 11 | -71258869848 |
| 12 | 1645797382177 |
| 13 | -41289185878227 |
| 14 | 1118136109703460 |
| 15 | -32509366699961371 |
| 16 | 1010047705084550823 |
| 17 | -33397162601828122332 |
| 18 | 1170937325957822375167 |
| 19 | -43391988679237460897205 |