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 | 480 |
| 6 | 7200 |
| 7 | 100800 |
| 8 | 1431360 |
| 9 | 21772800 |
| 10 | 370137600 |
| 11 | 7185024000 |
| 12 | 158150361600 |
| 13 | 3848298854400 |
| 14 | 100865282918400 |
| 15 | 2799294930432000 |
| 16 | 81599752346112000 |
| 17 | 2492894621048832000 |
| 18 | 79852538982408192000 |
| 19 | 2684220785621286912000 |