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 | 1089 |
| 2 | 10989 |
| 3 | 109989 |
| 4 | 1099989 |
| 5 | 10891089 |
| 6 | 10999989 |
| 7 | 108901089 |
| 8 | 109999989 |
| 9 | 1089001089 |
| 10 | 1098910989 |
| 11 | 1099999989 |
| 12 | 10890001089 |
| 13 | 10989010989 |
| 14 | 10999999989 |
| 15 | 108900001089 |
| 16 | 108910891089 |
| 17 | 109890010989 |
| 18 | 109989109989 |
| 19 | 109999999989 |
| 20 | 1089000001089 |
| 21 | 1089109891089 |