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 | -5 |
| 1 | 5 |
| 2 | -1 |
| 3 | 1 |
| 4 | -1 |
| 5 | 1 |
| 6 | -1 |
| 7 | 1 |
| 8 | -1 |
| 9 | 25 |
| 10 | -25 |
| 11 | 477481 |
| 12 | -477481 |
| 13 | 49 |
| 14 | -49 |
| 15 | 13082689 |
| 16 | -13082689 |
| 17 | 1924313689 |
| 18 | -1924313689 |
| 19 | 30489001321 |
| 20 | -30489001321 |
| 21 | 730192467169 |
| 22 | -730192467169 |
| 23 | 55867983514256281 |
| 24 | -55867983514256281 |
| 25 | 73155570928609 |