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 | 11 |
| 1 | 151 |
| 2 | 1551 |
| 3 | 15551 |
| 4 | 155551 |
| 5 | 1555551 |
| 6 | 15555551 |
| 7 | 155555551 |
| 8 | 1555555551 |
| 9 | 15555555551 |
| 10 | 155555555551 |
| 11 | 1555555555551 |
| 12 | 15555555555551 |
| 13 | 155555555555551 |
| 14 | 1555555555555551 |
| 15 | 15555555555555551 |
| 16 | 155555555555555551 |
| 17 | 1555555555555555551 |
| 18 | 15555555555555555551 |
| 19 | 155555555555555555551 |