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) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 24 |
| 4 | 192 |
| 5 | 1280 |
| 6 | 7680 |
| 7 | 43008 |
| 8 | 229376 |
| 9 | 1179648 |
| 10 | 5898240 |
| 11 | 28835840 |
| 12 | 138412032 |
| 13 | 654311424 |
| 14 | 3053453312 |
| 15 | 14092861440 |
| 16 | 64424509440 |
| 17 | 292057776128 |
| 18 | 1314259992576 |
| 19 | 5875515260928 |
| 20 | 26113401159680 |