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) |
|---|---|
| 1 | 1 |
| 2 | -4095 |
| 3 | 531442 |
| 4 | -16781311 |
| 5 | 244140626 |
| 6 | -2176254990 |
| 7 | 13841287202 |
| 8 | -68736258047 |
| 9 | 282430067923 |
| 10 | -999755863470 |
| 11 | 3138428376722 |
| 12 | -8918293480462 |
| 13 | 23298085122482 |
| 14 | -56680071092190 |
| 15 | 129746582562692 |
| 16 | -281543712968703 |
| 17 | 582622237229762 |
| 18 | -1156551128144685 |
| 19 | 2213314919066162 |
| 20 | -4096999772640686 |