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 | 0 |
| 6 | 720 |
| 7 | 10080 |
| 8 | 87360 |
| 9 | 604800 |
| 10 | 3674160 |
| 11 | 20512800 |
| 12 | 108044640 |
| 13 | 545688000 |
| 14 | 2671036368 |
| 15 | 12763951200 |
| 16 | 59856451200 |
| 17 | 276499641600 |
| 18 | 1261691128944 |
| 19 | 5699120476320 |
| 20 | 25525119703200 |
| 21 | 113497442856000 |
| 22 | 501533701110288 |
| 23 | 2204246146687200 |
| 24 | 9641611208433600 |