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 | 0 |
| 3 | 1 |
| 4 | -2 |
| 5 | 5 |
| 6 | -12 |
| 7 | 29 |
| 8 | -70 |
| 9 | 169 |
| 10 | -408 |
| 11 | 985 |
| 12 | -2378 |
| 13 | 5741 |
| 14 | -13860 |
| 15 | 33461 |
| 16 | -80782 |
| 17 | 195025 |
| 18 | -470832 |
| 19 | 1136689 |
| 20 | -2744210 |
| 21 | 6625109 |
| 22 | -15994428 |
| 23 | 38613965 |
| 24 | -93222358 |
| 25 | 225058681 |
| 26 | -543339720 |
| 27 | 1311738121 |
| 28 | -3166815962 |
| 29 | 7645370045 |
| 30 | -18457556052 |
| 31 | 44560482149 |