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 | 0 |
| 5 | 20 |
| 6 | 240 |
| 7 | 1260 |
| 8 | 5600 |
| 9 | 45360 |
| 10 | 383040 |
| 11 | 2451680 |
| 12 | 17128320 |
| 13 | 157769040 |
| 14 | 1902380480 |
| 15 | 18882623760 |
| 16 | 163633317120 |
| 17 | 2095059774080 |
| 18 | 30792478993920 |
| 19 | 346562329685760 |
| 20 | 3905491275514880 |
| 21 | 58609449249207360 |
| 22 | 866031730098205440 |