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 | 24 |
| 5 | 0 |
| 6 | 720 |
| 7 | 0 |
| 8 | 7000 |
| 9 | 15120 |
| 10 | 126000 |
| 11 | 0 |
| 12 | 1777776 |
| 13 | 0 |
| 14 | 23543520 |
| 15 | 55855800 |
| 16 | 274565720 |
| 17 | 0 |
| 18 | 5337775872 |
| 19 | 0 |
| 20 | 63026049424 |
| 21 | 117920013120 |
| 22 | 995265791520 |
| 23 | 0 |
| 24 | 15265486117744 |
| 25 | 14283091977000 |
| 26 | 216344919117600 |
| 27 | 240142901941800 |
| 28 | 2854493961432480 |
| 29 | 0 |
| 30 | 55689696384165720 |