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 | 2 |
| 2 | -3 |
| 3 | 6 |
| 4 | -10 |
| 5 | 19 |
| 6 | -35 |
| 7 | 72 |
| 8 | -150 |
| 9 | 343 |
| 10 | -803 |
| 11 | 2024 |
| 12 | -5226 |
| 13 | 14299 |
| 14 | -40027 |
| 15 | 117392 |
| 16 | -351798 |
| 17 | 1095735 |
| 18 | -3483403 |
| 19 | 11442896 |
| 20 | -38326586 |
| 21 | 132070827 |
| 22 | -463565299 |
| 23 | 1668391912 |
| 24 | -6110374070 |
| 25 | 22885849335 |
| 26 | -87147853011 |
| 27 | 338645273368 |
| 28 | -1336767522026 |
| 29 | 5375276276699 |