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 | 4 |
| 2 | 44 |
| 3 | 544 |
| 4 | 4544 |
| 5 | 44544 |
| 6 | 444544 |
| 7 | 4444544 |
| 8 | 54444544 |
| 9 | 454444544 |
| 10 | 5454444544 |
| 11 | 45454444544 |
| 12 | 545454444544 |
| 13 | 5545454444544 |
| 14 | 55545454444544 |
| 15 | 555545454444544 |
| 16 | 4555545454444544 |
| 17 | 44555545454444544 |
| 18 | 544555545454444544 |