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 | 20 |
| 2 | 380 |
| 3 | 3980 |
| 4 | 39980 |
| 5 | 399980 |
| 6 | 3999980 |
| 7 | 39999980 |
| 8 | 399999980 |
| 9 | 3999999980 |
| 10 | 39999999980 |
| 11 | 399999999980 |
| 12 | 3999999999980 |
| 13 | 39999999999980 |
| 14 | 399999999999980 |
| 15 | 3999999999999980 |
| 16 | 39999999999999980 |
| 17 | 399999999999999980 |