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 | 12 |
| 4 | 48 |
| 5 | 240 |
| 6 | 4320 |
| 7 | 50400 |
| 8 | 564480 |
| 9 | 9434880 |
| 10 | 166924800 |
| 11 | 2953843200 |
| 12 | 60354201600 |
| 13 | 1357490534400 |
| 14 | 31907254579200 |
| 15 | 808142759424000 |
| 16 | 22052620541952000 |
| 17 | 635257746579456000 |
| 18 | 19347973338710016000 |