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 | 7 |
| 2 | 773 |
| 3 | 77711 |
| 4 | 77773 |
| 5 | 7777709 |
| 6 | 77777719 |
| 7 | 777777701 |
| 8 | 777777773 |
| 9 | 77777777717 |
| 10 | 777777777713 |
| 11 | 777777777773 |
| 12 | 7777777777771 |
| 13 | 777777777777719 |
| 14 | 777777777777773 |
| 15 | 77777777777777711 |
| 16 | 777777777777777737 |
| 17 | 7777777777777777793 |
| 18 | 77777777777777777729 |
| 19 | 77777777777777777771 |