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 | 2 |
| 2 | 8 |
| 3 | 80 |
| 4 | 2240 |
| 5 | 215040 |
| 6 | 77414400 |
| 7 | 61931520000 |
| 8 | 170930995200000 |
| 9 | 1340099002368000000 |