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 | -3 |
| 3 | -1 |
| 4 | 49 |
| 5 | 255 |
| 6 | -275 |
| 7 | -13105 |
| 8 | -83775 |
| 9 | 170495 |
| 10 | 8290045 |
| 11 | 69257055 |
| 12 | -111005135 |
| 13 | -9684015745 |
| 14 | -109196883795 |
| 15 | -31470300625 |
| 16 | 17728458119425 |
| 17 | 276531029694975 |
| 18 | 904537471692925 |
| 19 | -44728487203650625 |
| 20 | -1000823562359108175 |
| 21 | -7110596979389965825 |