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 | 1 |
| 4 | 15 |
| 5 | 80 |
| 6 | 432 |
| 7 | 2352 |
| 8 | 12896 |
| 9 | 71136 |
| 10 | 394400 |
| 11 | 2196128 |
| 12 | 12273648 |
| 13 | 68811184 |
| 14 | 386838480 |
| 15 | 2179890000 |
| 16 | 12309739968 |
| 17 | 69641542848 |
| 18 | 394643939904 |
| 19 | 2239678552640 |
| 20 | 12727572969680 |
| 21 | 72415319422992 |
| 22 | 412470467298032 |