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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 96 |
| 6 | 3456 |
| 7 | 497664 |
| 8 | 286654464 |
| 9 | 825564856320 |
| 10 | 11888133931008000 |
| 11 | 1027134771639091200000 |
| 12 | 532466665617704878080000000 |
| 13 | 1932215036193527461576704000000000 |