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 | -7 |
| 2 | 131 |
| 3 | -231 |
| 4 | 14287 |
| 5 | -2695 |
| 6 | 153941 |
| 7 | -79079 |
| 8 | 8006287 |
| 9 | 4028409 |
| 10 | -1844246495 |
| 11 | -809434087 |
| 12 | 16807591453717 |
| 13 | 203438983033 |
| 14 | -10883405258173 |
| 15 | -69286922606055 |
| 16 | 359945895253332479 |
| 17 | 30552782191862777 |
| 18 | -279390115069297124593 |
| 19 | -16939504536585585383 |