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 | 0 |
| 1 | 54 |
| 2 | 594 |
| 3 | 5994 |
| 4 | 59994 |
| 5 | 599994 |
| 6 | 5999994 |
| 7 | 59999994 |
| 8 | 599999994 |
| 9 | 5999999994 |
| 10 | 59999999994 |
| 11 | 599999999994 |
| 12 | 5999999999994 |
| 13 | 59999999999994 |
| 14 | 599999999999994 |
| 15 | 5999999999999994 |
| 16 | 59999999999999994 |
| 17 | 599999999999999994 |
| 18 | 5999999999999999994 |
| 19 | 59999999999999999994 |
| 20 | 599999999999999999994 |