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 | 24 |
| 6 | 144 |
| 7 | 1008 |
| 8 | 8064 |
| 9 | 72576 |
| 10 | 653184 |
| 11 | 7185024 |
| 12 | 86220288 |
| 13 | 1120863744 |
| 14 | 15692092416 |
| 15 | 237124952064 |
| 16 | 3793999233024 |
| 17 | 64497986961408 |
| 18 | 1160963765305344 |
| 19 | 22058311540801536 |
| 20 | 441004037348818944 |
| 21 | 9261084784325197824 |
| 22 | 203743865255154352128 |
| 23 | 4686108900868550098944 |