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 | 19 |
| 2 | 109 |
| 3 | 199 |
| 4 | 1009 |
| 5 | 1999 |
| 6 | 10009 |
| 7 | 10099 |
| 8 | 100999 |
| 9 | 199999 |
| 10 | 1000099 |
| 11 | 1000999 |
| 12 | 19999999 |
| 13 | 1000000009 |
| 14 | 1000009999 |
| 15 | 1000099999 |
| 16 | 1009999999 |
| 17 | 10000000999 |
| 18 | 10000099999 |
| 19 | 10999999999 |
| 20 | 100999999999 |
| 21 | 1000000009999 |
| 22 | 1000000999999 |
| 23 | 1099999999999 |
| 24 | 10000000000099 |
| 25 | 10009999999999 |
| 26 | 100000000000099 |
| 27 | 100000009999999 |