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) |
|---|---|
| 3 | 0 |
| 4 | 3 |
| 5 | 30 |
| 6 | 210 |
| 7 | 1260 |
| 8 | 6944 |
| 9 | 36288 |
| 10 | 182880 |
| 11 | 897600 |
| 12 | 4316928 |
| 13 | 20427264 |
| 14 | 95373824 |
| 15 | 440294400 |
| 16 | 2013020160 |
| 17 | 9126248448 |
| 18 | 41069371392 |
| 19 | 183607050240 |
| 20 | 816037560320 |
| 21 | 3607758766080 |
| 22 | 15874168848384 |
| 23 | 69544044134400 |
| 24 | 303465064562688 |