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 | 0 |
| 2 | 3 |
| 3 | -3 |
| 4 | 10 |
| 5 | -18 |
| 6 | 42 |
| 7 | -87 |
| 8 | 190 |
| 9 | -405 |
| 10 | 873 |
| 11 | -1872 |
| 12 | 4024 |
| 13 | -8640 |
| 14 | 18561 |
| 15 | -39864 |
| 16 | 85627 |
| 17 | -183915 |
| 18 | 395034 |
| 19 | -848490 |
| 20 | 1822474 |
| 21 | -3914487 |
| 22 | 8407926 |
| 23 | -18059373 |
| 24 | 38789713 |
| 25 | -83316384 |
| 26 | 178955184 |
| 27 | -384377664 |
| 28 | 825604417 |
| 29 | -1773314928 |
| 30 | 3808901427 |
| 31 | -8181135699 |
| 32 | 17572253482 |
| 33 | -37743426306 |