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 | 3 |
| 2 | -9 |
| 3 | -198 |
| 4 | 1188 |
| 5 | 30213 |
| 6 | -220239 |
| 7 | -5945238 |
| 8 | 47541735 |
| 9 | 1325876283 |
| 10 | -11192990913 |
| 11 | -318640183182 |
| 12 | 2787445591416 |
| 13 | 80483342059224 |
| 14 | -722019579525288 |
| 15 | -21063846331387728 |
| 16 | 192542324985927324 |
| 17 | 5661585516173303268 |
| 18 | -52508399485861250604 |
| 19 | -1553593208517770295816 |