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 | 2 |
| 2 | 1 |
| 3 | 74 |
| 4 | -1 |
| 5 | -1 |
| 6 | 37 |
| 7 | 31746 |
| 8 | -1 |
| 9 | 24691358 |
| 10 | -1 |
| 11 | 2 |
| 12 | -1 |
| 13 | 17094 |
| 14 | 15873 |
| 15 | -1 |
| 16 | -1 |
| 17 | 130718954248366 |
| 18 | 12345679 |
| 19 | 11695906432748538 |
| 20 | -1 |
| 21 | 10582 |
| 22 | 1 |
| 23 | 96618357487922705314 |
| 24 | -1 |
| 25 | -1 |
| 26 | 8547 |
| 27 | 8230452674897119341563786 |
| 28 | -1 |
| 29 | 76628352490421455938697318 |
| 30 | -1 |
| 31 | 7168458781362 |
| 32 | -1 |
| 33 | 6734 |
| 34 | 65359477124183 |
| 35 | -1 |
| 36 | -1 |
| 37 | 6 |
| 38 | 5847953216374269 |
| 39 | 5698 |
| 40 | -1 |
| 41 | 542 |
| 42 | 5291 |
| 43 | 5167958656330749354 |