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 | 1 |
| 3 | -1 |
| 4 | -1 |
| 5 | 31 |
| 6 | -449 |
| 7 | 4223 |
| 8 | 377087 |
| 9 | -79232513 |
| 10 | 13509592063 |
| 11 | -74458331137 |
| 12 | -5113818652864513 |
| 13 | 11766261105083555839 |
| 14 | -22128578595003966668801 |
| 15 | -88147548436159218430476289 |
| 16 | 3787186430286106428653327941631 |
| 17 | -103331603080469761480767867413463041 |