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 | 1 |
| 3 | -2 |
| 4 | -22 |
| 5 | -134 |
| 6 | -418 |
| 7 | 1044 |
| 8 | 35352 |
| 9 | 371256 |
| 10 | 2662872 |
| 11 | 2256 |
| 12 | -348450672 |
| 13 | -7383337584 |
| 14 | -85166363280 |
| 15 | -224652273504 |
| 16 | 17983453809024 |
| 17 | 500248545941376 |
| 18 | 7414246148833152 |
| 19 | 13911378371907840 |
| 20 | -2620344425592796416 |
| 21 | -85017815816225598720 |
| 22 | -1321651042532303189760 |