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 | 0 |
| 2 | -1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 3 |
| 6 | 9 |
| 7 | 16 |
| 8 | 7 |
| 9 | -87 |
| 10 | -472 |
| 11 | -1567 |
| 12 | -3375 |
| 13 | -216 |
| 14 | 45927 |
| 15 | 308107 |
| 16 | 1372744 |
| 17 | 4351599 |
| 18 | 5711849 |
| 19 | -49345432 |
| 20 | -547773585 |
| 21 | -3517370859 |
| 22 | -16914970464 |
| 23 | -56474505155 |
| 24 | -25470754271 |
| 25 | 1593389360016 |
| 26 | 17323737305039 |
| 27 | 125785962635543 |
| 28 | 706598399399184 |