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 | 0 |
| 3 | 6 |
| 4 | 40 |
| 5 | 152 |
| 6 | 480 |
| 7 | 1376 |
| 8 | 3712 |
| 9 | 9600 |
| 10 | 24064 |
| 11 | 58880 |
| 12 | 141312 |
| 13 | 333824 |
| 14 | 778240 |
| 15 | 1794048 |
| 16 | 4096000 |
| 17 | 9273344 |
| 18 | 20840448 |
| 19 | 46530560 |
| 20 | 103284736 |
| 21 | 228065280 |
| 22 | 501219328 |
| 23 | 1096810496 |
| 24 | 2390753280 |
| 25 | 5192548352 |
| 26 | 11240734720 |
| 27 | 24259854336 |