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 | 14741 |
| 1 | 74747 |
| 2 | 1414741 |
| 3 | 1474141 |
| 4 | 14141414141 |
| 5 | 14141414741 |
| 6 | 14141474741 |
| 7 | 14147414741 |
| 8 | 14147474141 |
| 9 | 74141414147 |
| 10 | 1474741414141 |
| 11 | 7474141474747 |
| 12 | 7474741414747 |
| 13 | 14141474141414141 |
| 14 | 14147414747474741 |
| 15 | 14147474147474741 |