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) |
|---|---|
| 1 | 1 |
| 2 | -13 |
| 3 | 84 |
| 4 | -712 |
| 5 | 6916 |
| 6 | -55788 |
| 7 | 432584 |
| 8 | -3555212 |
| 9 | 28927916 |
| 10 | -229458788 |
| 11 | 1847086584 |
| 12 | -14858027212 |
| 13 | 118242773916 |
| 14 | -945499611788 |
| 15 | 7556178053084 |
| 16 | -60048635124212 |
| 17 | 477995366994916 |
| 18 | -3810212526827288 |
| 19 | 30296614848644584 |
| 20 | -240796293647346212 |
| 21 | 1916211884628153416 |