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 | 0 |
| 3 | 3 |
| 4 | -6 |
| 5 | 28 |
| 6 | -105 |
| 7 | 444 |
| 8 | -1897 |
| 9 | 8338 |
| 10 | -37305 |
| 11 | 169471 |
| 12 | -779537 |
| 13 | 3623500 |
| 14 | -16993990 |
| 15 | 80316081 |
| 16 | -382136133 |
| 17 | 1828896726 |
| 18 | -8798796709 |
| 19 | 42528048930 |
| 20 | -206413678447 |
| 21 | 1005623593109 |
| 22 | -4916026689088 |
| 23 | 24106987842416 |
| 24 | -118551374861525 |
| 25 | 584526569727010 |
| 26 | -2888995759466360 |