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 | 6 |
| 4 | 48 |
| 5 | 480 |
| 6 | 6480 |
| 7 | 100800 |
| 8 | 1774080 |
| 9 | 35199360 |
| 10 | 776563200 |
| 11 | 18840729600 |
| 12 | 498640665600 |
| 13 | 14297239756800 |
| 14 | 441470866636800 |
| 15 | 14605415016192000 |
| 16 | 515412006100992000 |
| 17 | 19325209343311872000 |
| 18 | 767215648278503424000 |