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 | 2 |
| 1 | 6 |
| 2 | 30 |
| 3 | 210 |
| 4 | 1890 |
| 5 | 20790 |
| 6 | 270270 |
| 7 | 1896516717212415135141110350293750000 |
| 8 | 1220462921565155916674902677397230198502690752000000000 |