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 | -1 |
| 3 | 3 |
| 4 | -53 |
| 5 | 65 |
| 6 | -1873 |
| 7 | 469 |
| 8 | -11191 |
| 9 | 55391 |
| 10 | -1031191 |
| 11 | 1334179 |
| 12 | -2126212148 |
| 13 | 5653970452 |
| 14 | -675022695 |
| 15 | 438925403269 |
| 16 | -67882510220729 |
| 17 | 74577815126027 |
| 18 | -91314328938731167 |
| 19 | 101372762616408631 |