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 | 0 |
| 5 | 0 |
| 6 | 720 |
| 7 | 4320 |
| 8 | 30960 |
| 9 | 256320 |
| 10 | 2399760 |
| 11 | 25022880 |
| 12 | 287250480 |
| 13 | 3597143040 |
| 14 | 48773612880 |
| 15 | 711607724640 |
| 16 | 11113078385520 |
| 17 | 184925331414720 |
| 18 | 3265974496290960 |
| 19 | 61006644910213920 |
| 20 | 1201583921745846960 |
| 21 | 24885771463659934080 |
| 22 | 540624959563046320080 |
| 23 | 12291921453805577987040 |