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 | -5 |
| 2 | -1 |
| 3 | 35 |
| 4 | -227 |
| 5 | -1435 |
| 6 | 27599 |
| 7 | 123095 |
| 8 | -2428187 |
| 9 | -18154423 |
| 10 | 1002748195 |
| 11 | 4095412475 |
| 12 | -11278566075977 |
| 13 | -1310672758291 |
| 14 | 9265563303353 |
| 15 | 564709713458975 |
| 16 | -387913690488413419 |
| 17 | -315149059886480239 |
| 18 | 381102197975912820173 |
| 19 | 221139612243078051395 |