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 | 1 |
| 4 | -1 |
| 5 | 1 |
| 6 | 1 |
| 7 | -11 |
| 8 | 41 |
| 9 | -83 |
| 10 | -77 |
| 11 | 1621 |
| 12 | -8503 |
| 13 | 25689 |
| 14 | -11283 |
| 15 | -436307 |
| 16 | 3380827 |
| 17 | -15378675 |
| 18 | 37938353 |
| 19 | 87204085 |
| 20 | -1755462619 |
| 21 | 12722279385 |
| 22 | -61250294425 |
| 23 | 164643256457 |
| 24 | 465385122833 |
| 25 | -10366591960879 |
| 26 | 88472237039417 |
| 27 | -527994960273655 |
| 28 | 2118908595206935 |
| 29 | -1118896610239543 |