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) |
|---|---|
| 3 | 0 |
| 4 | -1 |
| 5 | 0 |
| 6 | 0 |
| 7 | 4 |
| 8 | -1 |
| 9 | 26 |
| 10 | 45 |
| 11 | 94 |
| 12 | -1 |
| 13 | 196 |
| 14 | -1 |
| 15 | 370 |
| 16 | -1 |
| 17 | 641 |
| 18 | 743 |
| 19 | 999 |
| 20 | -1 |
| 21 | 1537 |
| 22 | 1429 |
| 23 | 2619 |