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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 5 |
| 4 | -77 |
| 5 | 399 |
| 6 | -124729 |
| 7 | 81549 |
| 8 | -23960365 |
| 9 | 283583443 |
| 10 | -478398640447 |
| 11 | 19740912828 |
| 12 | -11911591259019739 |
| 13 | 18262332208600 |
| 14 | -4514446693068714225 |
| 15 | 142267808222130386191 |
| 16 | -1912831808055538077885 |
| 17 | 39773048560156838355 |
| 18 | -43025628065750129034887540875 |
| 19 | 86435429204640847578555 |