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 | 422 |
| 3 | 174 |
| 4 | -1 |
| 5 | 22830 |
| 6 | 9216772051242 |
| 7 | 234374 |
| 8 | -1 |
| 9 | -1 |