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 | 1 |
| 2 | 3 |
| 3 | 54 |
| 4 | 3750 |
| 5 | 1009680 |
| 6 | 1058347920 |
| 7 | 4375678520640 |
| 8 | 71934792452208000 |
| 9 | 4719774805970453006400 |
| 10 | 1237727595442264073683462080 |
| 11 | 1298006134163762816201615178698880 |
| 12 | 5444432200219729912412940250057668378240 |