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 | 11 |
| 1 | 191 |
| 2 | 1991 |
| 3 | 19991 |
| 4 | 199991 |
| 5 | 1999991 |
| 6 | 19999991 |
| 7 | 199999991 |
| 8 | 1999999991 |
| 9 | 19999999991 |
| 10 | 199999999991 |
| 11 | 1999999999991 |
| 12 | 19999999999991 |
| 13 | 199999999999991 |
| 14 | 1999999999999991 |
| 15 | 19999999999999991 |
| 16 | 199999999999999991 |
| 17 | 1999999999999999991 |
| 18 | 19999999999999999991 |