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 | 1 |
| 3 | 9 |
| 4 | 105 |
| 5 | 38505 |
| 6 | 1771476585 |
| 7 | 10838310072981296745 |
| 8 | 140350834813144189858090274002849666665 |
| 9 | 68033174967769840440887906939858451149105560803546820641877549596291376780905 |