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 | 20 |
| 3 | 1960 |
| 4 | 18819920 |
| 5 | 1735166549767840 |
| 6 | 14749861913749949808286047759680 |
| 7 | 1065814268211609269094400465471990022332221793124358274759711360 |