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 | 2 |
| 2 | 4 |
| 3 | 2 |
| 4 | -32 |
| 5 | -198 |
| 6 | -416 |
| 7 | 2634 |
| 8 | 30720 |
| 9 | 107378 |
| 10 | -605696 |
| 11 | -10282094 |
| 12 | -46020608 |
| 13 | 304968874 |
| 14 | 6121832448 |
| 15 | 29994597338 |
| 16 | -279697555456 |
| 17 | -5729595393310 |
| 18 | -26849178681344 |
| 19 | 401845799334690 |
| 20 | 7714801999937536 |
| 21 | 29062583111892506 |
| 22 | -812705956979802112 |