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 | -4 |
| 2 | 144 |
| 3 | -43264 |
| 4 | 106832896 |
| 5 | -2155963622400 |
| 6 | 354617391605760000 |
| 7 | -474686810341051524710400 |
| 8 | 5166329306435680284163452174336 |
| 9 | -456900249341808231214942590547243565056 |