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 | 3 |
| 3 | 20 |
| 4 | 138 |
| 5 | 1488 |
| 6 | 20400 |
| 7 | 317520 |
| 8 | 5911920 |
| 9 | 126080640 |
| 10 | 2999566080 |
| 11 | 79604985600 |