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 | 9 |
| 3 | -11 |
| 4 | 59 |
| 5 | -267 |
| 6 | 433 |
| 7 | -2041 |
| 8 | 9753 |
| 9 | -15443 |
| 10 | 73547 |
| 11 | -349875 |
| 12 | 555073 |
| 13 | -2641297 |
| 14 | 12569673 |
| 15 | -19938491 |
| 16 | 94883195 |
| 17 | -451526331 |
| 18 | 716237425 |
| 19 | -3408408073 |
| 20 | 16219834713 |
| 21 | -25728821507 |
| 22 | 122437560587 |
| 23 | -582652240611 |
| 24 | 924236100865 |
| 25 | -4398227463841 |
| 26 | 20930155058697 |
| 27 | -33200601349355 |