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 | 7 |
| 2 | 59 |
| 3 | 557 |
| 4 | 5557 |
| 5 | 55579 |
| 6 | 555557 |
| 7 | 5555567 |
| 8 | 55555559 |
| 9 | 555555587 |
| 10 | 5555555557 |
| 11 | 55555555619 |
| 12 | 555555555559 |
| 13 | 5555555555593 |
| 14 | 55555555555573 |
| 15 | 555555555555557 |
| 16 | 5555555555555573 |
| 17 | 55555555555555639 |
| 18 | 555555555555555559 |
| 19 | 5555555555555555621 |
| 20 | 55555555555555555567 |
| 21 | 555555555555555555619 |