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 | -17 |
| 2 | 409 |
| 3 | -510 |
| 4 | 105599 |
| 5 | -22270 |
| 6 | 783607 |
| 7 | -744770 |
| 8 | 132547199 |
| 9 | -26478486 |
| 10 | 8708240645 |
| 11 | -496587850 |
| 12 | 1903871040587 |
| 13 | -71670092702 |
| 14 | -338854110137 |
| 15 | 12249601191150 |
| 16 | 28492203321193183 |
| 17 | -4370053436967718 |
| 18 | -2259849766310584691 |
| 19 | 1846812141916088230 |
| 20 | 3101187019750975673389 |