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 | 6 |
| 3 | -27 |
| 4 | 161 |
| 5 | -1205 |
| 6 | 10799 |
| 7 | -113043 |
| 8 | 1351461 |
| 9 | -18183781 |
| 10 | 271784079 |
| 11 | -4469044657 |
| 12 | 80160267791 |
| 13 | -1557710354083 |
| 14 | 32597642189657 |
| 15 | -730897865864471 |
| 16 | 17480390183397209 |
| 17 | -444198879957594857 |
| 18 | 11951585821669838395 |
| 19 | -339434402344422296117 |