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 | -1 |
| 4 | -1 |
| 5 | 3 |
| 6 | -5 |
| 7 | -13 |
| 8 | 83 |
| 9 | -1149 |
| 10 | -94301 |
| 11 | 108447299 |
| 12 | -10226797095997 |
| 13 | -1109068512255229713405 |
| 14 | 11342218640394605506848882609549187 |
| 15 | -12579297553175979435284002182896862386417808141640587517 |