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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 5 |
| 6 | 5 |
| 7 | 7 |
| 8 | 7 |
| 9 | -3 |
| 10 | -3 |
| 11 | 121 |
| 12 | 121 |
| 13 | -1261 |
| 14 | -1261 |
| 15 | 20583 |
| 16 | 20583 |
| 17 | -888403 |
| 18 | -888403 |
| 19 | 24729925 |
| 20 | 24729925 |
| 21 | -862992399 |
| 22 | -862992399 |
| 23 | 36913939769 |
| 24 | 36913939769 |
| 25 | -1899853421885 |
| 26 | -1899853421885 |