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 | 4 |
| 2 | 192 |
| 3 | 23040 |
| 4 | 5160960 |
| 5 | 1857945600 |
| 6 | 980995276800 |
| 7 | 714164561510400 |
| 8 | 685597979049984000 |
| 9 | 839171926357180416000 |
| 10 | 1275541328062914232320000 |
| 11 | 2357200374260265501327360000 |
| 12 | 5204698426366666226930810880000 |
| 13 | 13532215908553332190020108288000000 |