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 | 277 |
| 3 | 1777 |
| 4 | 47777 |
| 5 | 2477777 |
| 6 | 16777777 |
| 7 | 137777777 |
| 8 | 577777777 |
| 9 | 1777777777 |
| 10 | 67777777777 |
| 11 | 377777777777 |
| 12 | 16777777777777 |
| 13 | 17777777777777 |
| 14 | 577777777777777 |
| 15 | 2777777777777777 |
| 16 | 157777777777777777 |
| 17 | 377777777777777777 |
| 18 | 2777777777777777777 |
| 19 | 97777777777777777777 |
| 20 | 2477777777777777777777 |