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 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | -5 |
| 4 | -1 |
| 5 | 31 |
| 6 | 65 |
| 7 | -90 |
| 8 | -641 |
| 9 | -644 |
| 10 | 3329 |
| 11 | 11386 |
| 12 | -1471 |
| 13 | -87021 |
| 14 | -164634 |
| 15 | 317935 |
| 16 | 1881471 |
| 17 | 1418719 |
| 18 | -11370760 |
| 19 | -33937951 |
| 20 | 17468929 |
| 21 | 294971868 |
| 22 | 468897758 |
| 23 | -1304743033 |
| 24 | -6275603903 |
| 25 | -2804572819 |
| 26 | 42665919997 |
| 27 | 109181454826 |
| 28 | -106020803386 |
| 29 | -1063546684834 |
| 30 | -1362993953395 |