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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 24 |
| 6 | 120 |
| 7 | 720 |
| 8 | 4200 |
| 9 | 24192 |
| 10 | 151200 |
| 11 | 1056000 |
| 12 | 7286400 |
| 13 | 54743040 |
| 14 | 442041600 |
| 15 | 3997593600 |
| 16 | 29081052000 |
| 17 | 244365721600 |
| 18 | 2164235673600 |
| 19 | 21996748800000 |
| 20 | 197620929792000 |
| 21 | 2090405560320000 |
| 22 | 22475789107200000 |
| 23 | 280198170869760000 |
| 24 | 2772753817946112000 |