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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 72 |
| 5 | 6912 |
| 6 | 4147200 |
| 7 | 17915904000 |
| 8 | 632073093120000 |
| 9 | 203881496916787200000 |
| 10 | 665860658410473652224000000 |
| 11 | 24162751572399267891904512000000000 |
| 12 | 10609496941616618062463314270617600000000000 |