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 | 4 |
| 6 | 39 |
| 7 | -158 |
| 8 | 211 |
| 9 | -186 |
| 10 | -33722 |
| 11 | 55130 |
| 12 | 192039 |
| 13 | -4032991 |