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 | 1 |
| 2 | -3 |
| 3 | 8 |
| 4 | -18 |
| 5 | 47 |
| 6 | -105 |
| 7 | 274 |
| 8 | -612 |
| 9 | 1597 |
| 10 | -3567 |
| 11 | 9308 |
| 12 | -20790 |
| 13 | 54251 |
| 14 | -121173 |
| 15 | 316198 |
| 16 | -706248 |
| 17 | 1842937 |
| 18 | -4116315 |
| 19 | 10741424 |
| 20 | -23991642 |
| 21 | 62605607 |
| 22 | -139833537 |
| 23 | 364892218 |
| 24 | -815009580 |
| 25 | 2126747701 |
| 26 | -4750223943 |
| 27 | 12395593988 |
| 28 | -27686334078 |
| 29 | 72246816227 |