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 | 7 |
| 1 | 474 |
| 2 | 44744 |
| 3 | 4447444 |
| 4 | 444474444 |
| 5 | 44444744444 |
| 6 | 4444447444444 |
| 7 | 444444474444444 |
| 8 | 44444444744444444 |
| 9 | 4444444447444444444 |
| 10 | 444444444474444444444 |
| 11 | 44444444444744444444444 |
| 12 | 4444444444447444444444444 |
| 13 | 444444444444474444444444444 |
| 14 | 44444444444444744444444444444 |
| 15 | 4444444444444447444444444444444 |