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 | 3 |
| 3 | -4 |
| 4 | 17 |
| 5 | -41 |
| 6 | 42 |
| 7 | -289 |
| 8 | 1171 |
| 9 | -1739 |
| 10 | 1753 |
| 11 | -19157 |
| 12 | 19262 |
| 13 | -249251 |
| 14 | 250241 |
| 15 | -249383 |
| 16 | 200107 |
| 17 | -1696405 |
| 18 | 1700409 |
| 19 | -32239703 |
| 20 | 161504821 |
| 21 | -161227687 |
| 22 | 161479627 |
| 23 | -3708740681 |
| 24 | 3713590526 |
| 25 | -18545643343 |
| 26 | 18566236531 |
| 27 | -55641506293 |
| 28 | 55694623643 |
| 29 | -230529988171 |