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 | 9 |
| 2 | 180 |
| 3 | 2700 |
| 4 | 36000 |
| 5 | 450000 |
| 6 | 5400000 |
| 7 | 63000000 |
| 8 | 720000000 |
| 9 | 8100000000 |
| 10 | 90000000000 |
| 11 | 990000000000 |
| 12 | 10800000000000 |
| 13 | 117000000000000 |
| 14 | 1260000000000000 |
| 15 | 13500000000000000 |
| 16 | 144000000000000000 |
| 17 | 1530000000000000000 |
| 18 | 16200000000000000000 |
| 19 | 171000000000000000000 |
| 20 | 1800000000000000000000 |