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 | 5 |
| 2 | 7 |
| 3 | 47 |
| 4 | 457 |
| 5 | 547 |
| 6 | 557 |
| 7 | 577 |
| 8 | 757 |
| 9 | 4447 |
| 10 | 4457 |
| 11 | 4547 |
| 12 | 5477 |
| 13 | 5557 |
| 14 | 7457 |
| 15 | 7477 |
| 16 | 7547 |
| 17 | 7577 |
| 18 | 7757 |
| 19 | 44777 |
| 20 | 45557 |
| 21 | 45757 |
| 22 | 47777 |
| 23 | 54547 |
| 24 | 54577 |
| 25 | 55457 |
| 26 | 55547 |
| 27 | 57457 |
| 28 | 57557 |
| 29 | 74747 |
| 30 | 75557 |
| 31 | 75577 |
| 32 | 77447 |
| 33 | 77477 |
| 34 | 77557 |
| 35 | 77747 |
| 36 | 444547 |
| 37 | 444557 |
| 38 | 445447 |
| 39 | 445477 |
| 40 | 445747 |
| 41 | 447757 |