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 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 20 |
| 5 | 336 |
| 6 | 154440 |
| 7 | 8204716800 |
| 8 | 5778574175582208000 |
| 9 | 43004718293359780142729736192000000 |
| 10 | 1300207208378579462193856077468752280037294977727353323520000000 |