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 | 2 |
| 3 | 12 |
| 4 | 168 |
| 5 | 2880 |
| 6 | 64080 |
| 7 | 1723680 |
| 8 | 54633600 |
| 9 | 1992936960 |
| 10 | 82261267200 |
| 11 | 3790579161600 |
| 12 | 192895381324800 |
| 13 | 10744251136819200 |
| 14 | 650181362358528000 |
| 15 | 42476922345521664000 |
| 16 | 2979716339168464896000 |
| 17 | 223385082959833546752000 |