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) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | -80 |
| 3 | 820 |
| 4 | -8180 |
| 5 | 81820 |
| 6 | -818180 |
| 7 | 8181820 |
| 8 | -81818180 |
| 9 | 818181820 |
| 10 | -8181818180 |
| 11 | 81818181820 |
| 12 | -818181818180 |
| 13 | 8181818181820 |
| 14 | -81818181818180 |
| 15 | 818181818181820 |
| 16 | -8181818181818180 |
| 17 | 81818181818181820 |