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 | 100 |
| 3 | 720 |
| 4 | 9792 |
| 5 | 90900 |
| 6 | 990000 |
| 7 | 9090900 |
| 8 | 94117632 |
| 9 | 681410880 |
| 10 | 9897840000 |
| 11 | 86925373920 |
| 12 | 979102080000 |
| 13 | 9080325951840 |
| 14 | 95255567232000 |
| 15 | 712493107200000 |
| 16 | 9926748531589120 |
| 17 | 90004044661864320 |
| 18 | 989999010000000000 |
| 19 | 9090909090909090900 |
| 20 | 97910150554895155200 |