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 | 8 |
| 5 | 220 |
| 6 | 4200 |
| 7 | 71400 |
| 8 | 1176000 |
| 9 | 19474560 |
| 10 | 330220800 |
| 11 | 5787936000 |
| 12 | 105380352000 |
| 13 | 1997835840000 |
| 14 | 39477236198400 |
| 15 | 813155511168000 |
| 16 | 17453093898240000 |
| 17 | 390070546145280000 |
| 18 | 9070029416448000000 |
| 19 | 219204470936715264000 |