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 | 10 |
| 1 | 19 |
| 2 | 109 |
| 3 | 1009 |
| 4 | 10009 |
| 5 | 100009 |
| 6 | 1000009 |
| 7 | 10000009 |
| 8 | 100000009 |
| 9 | 1000000009 |
| 10 | 10000000009 |
| 11 | 100000000009 |
| 12 | 1000000000009 |
| 13 | 10000000000009 |
| 14 | 100000000000009 |
| 15 | 1000000000000009 |
| 16 | 10000000000000009 |
| 17 | 100000000000000009 |
| 18 | 1000000000000000009 |
| 19 | 10000000000000000009 |
| 20 | 100000000000000000009 |