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 | 70007020020 |
| 2 | 27272070272700 |
| 3 | 20720272227227700077007700020 |
| 4 | 22200020770272007007202277772702722200 |