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 | 2 |
| 2 | 2 |
| 3 | 222 |
| 4 | 20 |
| 5 | 20 |
| 6 | 222 |
| 7 | 222222 |
| 8 | 200 |
| 9 | 222222222 |
| 10 | 20 |
| 11 | 2222222222 |
| 12 | 2220 |
| 13 | 222222222222 |
| 14 | 222222 |
| 15 | 2220 |
| 16 | 2000 |
| 17 | 2222222222222222 |
| 18 | 222222222 |
| 19 | 222222222222222222 |
| 20 | 20 |
| 21 | 222222 |