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 | 13 |
| 3 | -43 |
| 4 | 5647 |
| 5 | -3401 |
| 6 | 2763977 |
| 7 | -10326059 |
| 8 | 876576493 |
| 9 | -1665984623 |
| 10 | 1156096889861 |
| 11 | -2220482068331 |
| 12 | 75970695882225719 |
| 13 | -1088498788093641 |
| 14 | 855021689397409453 |
| 15 | -3324381371618385007 |
| 16 | 4010325276269988793421 |