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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 105 |
| 4 | 13515 |
| 5 | 1771476585 |
| 6 | 3804217000364127435 |
| 7 | 140350834813144189858090274002849666665 |
| 8 | 23879457134773177491341539034414728352082211931046871698790017205810876429515 |