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) |
|---|---|
| 3 | 1 |
| 4 | -1220 |
| 5 | 1637362 |
| 6 | -2177691460 |
| 7 | 2898705467483 |
| 8 | -3858153003126520 |
| 9 | 5135204548028317764 |
| 10 | -6834956902420811530200 |
| 11 | 9097327679593690752247605 |
| 12 | -12108543136400139930131294300 |
| 13 | 16116470915170412804822871108406 |