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) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 105 |
| 9 | 3780 |
| 10 | 81900 |
| 11 | 1386000 |
| 12 | 20207880 |
| 13 | 266666400 |
| 14 | 3277354080 |
| 15 | 38198160000 |
| 16 | 427365818880 |
| 17 | 4629059635200 |
| 18 | 48842864179200 |
| 19 | 504335346278400 |
| 20 | 5114054709319680 |
| 21 | 51064119467827200 |
| 22 | 503151159589478400 |
| 23 | 4900668252598272000 |
| 24 | 47248486914198011904 |
| 25 | 451429610841538560000 |