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 | -1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 4 |
| 6 | 5 |
| 7 | 29 |
| 8 | 41 |
| 9 | 55 |
| 10 | 71 |
| 11 | 881 |
| 12 | 791 |
| 13 | 9360 |
| 14 | 10009 |
| 15 | 1079 |
| 16 | 30239 |
| 17 | -1 |
| 18 | 246960 |
| 19 | -1 |
| 20 | 636481 |
| 21 | 1360800 |
| 22 | 3160079 |
| 23 | -1 |
| 24 | 2162161 |