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 | 1 |
| 3 | -2 |
| 4 | 3 |
| 5 | -4 |
| 6 | 9 |
| 7 | -14 |
| 8 | 23 |
| 9 | -40 |
| 10 | 69 |
| 11 | -114 |
| 12 | 195 |
| 13 | -332 |
| 14 | 561 |
| 15 | -950 |
| 16 | 1615 |
| 17 | -2736 |
| 18 | 4637 |
| 19 | -7866 |
| 20 | 13339 |
| 21 | -22612 |
| 22 | 38345 |
| 23 | -65022 |
| 24 | 110247 |
| 25 | -186936 |
| 26 | 316981 |
| 27 | -537474 |
| 28 | 911347 |
| 29 | -1545308 |
| 30 | 2620257 |
| 31 | -4442950 |
| 32 | 7533567 |
| 33 | -12774080 |
| 34 | 21659981 |
| 35 | -36727114 |
| 36 | 62275275 |
| 37 | -105595236 |
| 38 | 179049465 |
| 39 | -303600014 |