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 | -99 |
| 3 | 299 |
| 4 | 49401 |
| 5 | -249001 |
| 6 | -60251499 |
| 7 | 425252099 |
| 8 | 136795497201 |
| 9 | -1241382296401 |
| 10 | -498990299504499 |
| 11 | 5534485665505499 |
| 12 | 2669489641160743401 |
| 13 | -34991633084859742201 |
| 14 | -19690651784477632959099 |
| 15 | 297813229679687736760499 |
| 16 | 191527704666360326602988001 |