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) |
|---|---|
| 1 | 4 |
| 2 | 24 |
| 3 | 168 |
| 4 | 864 |
| 5 | 6200 |
| 6 | 30240 |
| 7 | 223944 |
| 8 | 1119744 |
| 9 | 7457184 |
| 10 | 37200000 |
| 11 | 277618528 |
| 12 | 1254113280 |
| 13 | 10445497920 |
| 14 | 51618196224 |
| 15 | 365601600000 |
| 16 | 1770091315200 |
| 17 | 13439285266176 |
| 18 | 62336092492800 |
| 19 | 484935499902880 |
| 20 | 2179146240000000 |
| 21 | 17141125020596640 |
| 22 | 86330728271779200 |