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 | -1 |
| 2 | 3 |
| 3 | -22 |
| 4 | 224 |
| 5 | -2759 |
| 6 | 41629 |
| 7 | -743319 |
| 8 | 15285861 |
| 9 | -355719616 |
| 10 | 9242332881 |
| 11 | -265191971970 |
| 12 | 8328195163545 |
| 13 | -284124989856012 |
| 14 | 10463788330880961 |
| 15 | -413744821089831397 |
| 16 | 17482192791456272614 |
| 17 | -786119610413822514764 |
| 18 | 37482612103603819839034 |
| 19 | -1888918995730788198553380 |