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 | 0 |
| 4 | 3 |
| 5 | -7 |
| 6 | 3 |
| 7 | 31 |
| 8 | -105 |
| 9 | 101 |
| 10 | 419 |
| 11 | -1971 |
| 12 | 2923 |
| 13 | 5800 |
| 14 | -40388 |
| 15 | 81147 |
| 16 | 64075 |
| 17 | -854408 |
| 18 | 2204543 |
| 19 | -56096 |
| 20 | -18070916 |
| 21 | 58866158 |
| 22 | -38939227 |
| 23 | -371701743 |
| 24 | 1544696638 |
| 25 | -1870286829 |
| 26 | -7166094999 |
| 27 | 39743193694 |
| 28 | -68677654555 |