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 | 720 |
| 2 | 1779148800 |
| 3 | 148953184174080000 |
| 4 | 126983900296423931904000000 |
| 5 | 614812159599342234168301977600000000 |
| 6 | 11942354952042770431904585727413846016000000000 |