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 | 2 |
| 1 | 5 |
| 2 | 557 |
| 3 | 5557 |
| 4 | 155557 |
| 5 | 555557 |
| 6 | 15555557 |
| 7 | 55555553 |
| 8 | 3555555551 |
| 9 | 5555555557 |
| 10 | 525555555557 |
| 11 | 555555555551 |
| 12 | 5555555555551 |
| 13 | 355555555555559 |
| 14 | 555555555555557 |
| 15 | 51555555555555551 |
| 16 | 545555555555555551 |
| 17 | 555555555555555559 |
| 18 | 15555555555555555557 |
| 19 | 155555555555555555551 |