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 | 20 |
| 2 | 520 |
| 3 | 5880 |
| 4 | 48720 |
| 5 | 341880 |
| 6 | 2162160 |
| 7 | 12732720 |
| 8 | 71179680 |
| 9 | 382444920 |
| 10 | 1991669680 |
| 11 | 10113543440 |
| 12 | 50297301600 |
| 13 | 245807780400 |
| 14 | 1183546677600 |
| 15 | 5626112450400 |
| 16 | 26447537160000 |
| 17 | 123113285479800 |
| 18 | 568139770321200 |
| 19 | 2601623487262800 |
| 20 | 11830908080191200 |
| 21 | 53465154668125200 |
| 22 | 240246019677549600 |