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 | 199 |
| 3 | 1999 |
| 4 | 49999 |
| 5 | 199999 |
| 6 | 2999999 |
| 7 | 19999999 |
| 8 | 799999999 |
| 9 | 10999999999 |
| 10 | 59999999999 |
| 11 | 1099999999999 |
| 12 | 34999999999999 |
| 13 | 59999999999999 |
| 14 | 499999999999999 |
| 15 | 14999999999999999 |
| 16 | 139999999999999999 |
| 17 | 1099999999999999999 |
| 18 | 20999999999999999999 |
| 19 | 29999999999999999999 |
| 20 | 2099999999999999999999 |