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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 30 |
| 6 | 360 |
| 7 | 4200 |
| 8 | 50400 |
| 9 | 635040 |
| 10 | 8467200 |
| 11 | 119750400 |
| 12 | 1796256000 |
| 13 | 28540512000 |
| 14 | 479480601600 |
| 15 | 8499883392000 |
| 16 | 158664489984000 |
| 17 | 3112264995840000 |
| 18 | 64023737057280000 |
| 19 | 1378644471300096000 |
| 20 | 31019500604252160000 |
| 21 | 728045925946859520000 |
| 22 | 17796678189812121600000 |