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 | 2 |
| 3 | 3 |
| 4 | -4 |
| 5 | -83 |
| 6 | -658 |
| 7 | -4193 |
| 8 | -22440 |
| 9 | -83975 |
| 10 | 120122 |
| 11 | 7476315 |
| 12 | 112365332 |
| 13 | 1294231525 |
| 14 | 12752263526 |
| 15 | 105731717431 |
| 16 | 610305421872 |
| 17 | -1116308339087 |
| 18 | -115998206237710 |
| 19 | -2570453790514893 |
| 20 | -43180432963618900 |
| 21 | -622814297059769699 |
| 22 | -7810135072307898658 |