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 | 6 |
| 4 | -152 |
| 5 | 6670 |
| 6 | -451152 |
| 7 | 43685208 |
| 8 | -5741360256 |
| 9 | 984176280288 |
| 10 | -213379094227200 |
| 11 | 57100689621382176 |
| 12 | -18489130293293779968 |
| 13 | 7125765731670143814672 |
| 14 | -3223822934974620319272960 |
| 15 | 1692009521117003600170128000 |
| 16 | -1019755541584493644326799048704 |