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) |
|---|---|
| 4 | 6 |
| 5 | 85 |
| 6 | 900 |
| 7 | 9450 |
| 8 | 104160 |
| 9 | 1224720 |
| 10 | 15422400 |
| 11 | 207900000 |
| 12 | 2993760000 |
| 13 | 45924278400 |
| 14 | 748280332800 |
| 15 | 12913284384000 |
| 16 | 235381386240000 |
| 17 | 4520194398720000 |
| 18 | 91233825306624000 |
| 19 | 1931115968990208000 |
| 20 | 42778526977105920000 |
| 21 | 989887004576870400000 |
| 22 | 23885015465274163200000 |