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 | 1 |
| 5 | 6 |
| 6 | 18 |
| 7 | 120 |
| 8 | 1260 |
| 9 | 1485540 |
| 10 | 28667100 |
| 11 | 28667100 |
| 12 | 842889105240 |
| 13 | 2281585556250 |
| 14 | 163881570370980 |
| 15 | 45187548280664790 |