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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 60 |
| 6 | 240 |
| 7 | 1260 |
| 8 | 48384 |
| 9 | 423360 |
| 10 | 3844800 |
| 11 | 38253600 |
| 12 | 896797440 |
| 13 | 14322147840 |
| 14 | 216997522560 |
| 15 | 3350656108800 |
| 16 | 74820944056320 |
| 17 | 1621271286835200 |
| 18 | 34293811249152000 |
| 19 | 727304513980262400 |
| 20 | 18147791755697356800 |
| 21 | 476653146551318016000 |