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 | -2 |
| 3 | 16 |
| 4 | -206 |
| 5 | 3682 |
| 6 | -84236 |
| 7 | 2348704 |
| 8 | -77241380 |
| 9 | 2926735516 |
| 10 | -125540336024 |
| 11 | 6013069027648 |
| 12 | -318093606114536 |
| 13 | 18418565715581656 |
| 14 | -1158626159228481488 |
| 15 | 78679416565851286144 |
| 16 | -5736477278907382585328 |
| 17 | 446936684375920051751440 |
| 18 | -37056888825921886749507872 |