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 | 0 |
| 4 | 49920 |
| 5 | 18936480 |
| 6 | 1293857280 |
| 7 | 34839270480 |
| 8 | 518880929280 |
| 9 | 5122755187200 |
| 10 | 37376074229760 |
| 11 | 216261381584160 |
| 12 | 1041571537839360 |
| 13 | 4323020652281760 |
| 14 | 15864787390932480 |
| 15 | 52496402135289840 |
| 16 | 159036030441200640 |
| 17 | 446469968164496640 |
| 18 | 1172916400659517440 |