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 | 3 |
| 2 | 9 |
| 3 | 31 |
| 4 | 99 |
| 5 | 316 |
| 6 | 999 |
| 7 | 3162 |
| 8 | 9999 |
| 9 | 31622 |
| 10 | 99999 |
| 11 | 316227 |
| 12 | 999999 |
| 13 | 3162277 |
| 14 | 9999999 |
| 15 | 31622776 |
| 16 | 99999999 |
| 17 | 316227766 |
| 18 | 999999999 |
| 19 | 3162277660 |
| 20 | 9999999999 |
| 21 | 31622776601 |
| 22 | 99999999999 |
| 23 | 316227766016 |
| 24 | 999999999999 |
| 25 | 3162277660168 |