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 | 1 |
| 2 | 6 |
| 3 | 60 |
| 4 | 900 |
| 5 | 18480 |
| 6 | 487560 |
| 7 | 15824880 |
| 8 | 612504240 |
| 9 | 27619664640 |
| 10 | 1425084870240 |
| 11 | 82937356685760 |
| 12 | 5381249970008640 |
| 13 | 385518151040336640 |
| 14 | 30248651895457718400 |
| 15 | 2581418447382311243520 |
| 16 | 238181756821410417488640 |
| 17 | 23637327769847150582661120 |
| 18 | 2511570244361817605178754560 |
| 19 | 284573826857792109743033564160 |