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 | 2 |
| 2 | 96 |
| 3 | 1620 |
| 4 | 17920 |
| 5 | 157500 |
| 6 | 1197504 |
| 7 | 8240232 |
| 8 | 52715520 |
| 9 | 318995820 |
| 10 | 1847560000 |
| 11 | 10328229912 |
| 12 | 56073378816 |
| 13 | 297051536600 |
| 14 | 1541119305600 |
| 15 | 7852824450000 |
| 16 | 39392404439040 |
| 17 | 194905125100620 |
| 18 | 952671403252800 |