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 | 1 |
| 3 | -3 |
| 4 | 17 |
| 5 | -155 |
| 6 | 2073 |
| 7 | -38227 |
| 8 | 929569 |
| 9 | -28820619 |
| 10 | 1109652905 |
| 11 | -51943281731 |
| 12 | 2905151042481 |
| 13 | -191329672483963 |
| 14 | 14655626154768697 |
| 15 | -1291885088448017715 |
| 16 | 129848163681107301953 |
| 17 | -14761446733784164001387 |
| 18 | 1884515541728818675112649 |
| 19 | -268463531464165471482681379 |