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 | 2 |
| 1 | 4 |
| 2 | 24 |
| 3 | 720 |
| 4 | 712800 |
| 5 | 666860040000 |
| 6 | 597568733024952150000000 |
| 7 | 474258018883889933710067708314342382812500000000 |