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 | 4 |
| 3 | 22 |
| 4 | 1660 |
| 5 | 673600 |
| 6 | 896315680 |
| 7 | 1430468698240 |
| 8 | 27959577476915200 |
| 9 | 2959021586728806707200 |
| 10 | 1022333042228611529224192000 |
| 11 | 420758775616050043741512977612800 |