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 | 900 |
| 2 | 9000 |
| 3 | 90000 |
| 4 | 900000 |
| 5 | 9000000 |
| 6 | 90000000 |
| 7 | 700000000 |
| 8 | 9000000000 |
| 9 | 90000000000 |
| 10 | 900000000000 |
| 11 | 0 |
| 12 | 90000000000000 |
| 13 | 0 |
| 14 | 7000000000000000 |
| 15 | 90000000000000000 |