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) |
|---|---|
| 1 | -1 |
| 2 | 2 |
| 3 | -22 |
| 4 | 203 |
| 5 | -2285 |
| 6 | 33855 |
| 7 | -609345 |
| 8 | 12420372 |
| 9 | -284964519 |
| 10 | 7347342215 |
| 11 | -209807114169 |
| 12 | 6554034238459 |
| 13 | -222469737401739 |
| 14 | 8159109186320903 |
| 15 | -321461264348047819 |
| 16 | 13538455640979049698 |
| 17 | -606976994365011212414 |
| 18 | 28864017965496692865925 |
| 19 | -1451086990386146504580735 |