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 | 5 |
| 2 | 55 |
| 3 | 5005 |
| 4 | 505505 |
| 5 | 5005005005 |
| 6 | 50055055055005 |
| 7 | 50005050055005050005 |
| 8 | 5000005005005005005005000005 |
| 9 | 50000050055050055055055005055005000005 |