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 | -6 |
| 4 | -54 |
| 5 | -4470 |
| 6 | -30229110 |
| 7 | -1388162822415990 |
| 8 | -2926650008246700930753649260150 |
| 9 | -13001299396349738096788020339357180951040927696209747704510070 |