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 | -6 |
| 2 | 28 |
| 3 | -72 |
| 4 | -176 |
| 5 | 1824 |
| 6 | 11968 |
| 7 | -177792 |
| 8 | -1062656 |
| 9 | 25864704 |
| 10 | 155204608 |
| 11 | -5535270912 |
| 12 | -33211559936 |
| 13 | 1633165123584 |
| 14 | 9798991003648 |
| 15 | -635421070098432 |
| 16 | -3812526419542016 |
| 17 | 315212388818878464 |
| 18 | 1891274332917465088 |
| 19 | -194181169538677604352 |
| 20 | -1165087017232048848896 |