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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 240 |
| 5 | 3360 |
| 6 | 60480 |
| 7 | 1330560 |
| 8 | 34594560 |
| 9 | 1037836800 |
| 10 | 35286451200 |
| 11 | 1340885145600 |
| 12 | 56317176115200 |
| 13 | 2590590101299200 |
| 14 | 129529505064960000 |
| 15 | 6994593273507840000 |
| 16 | 405686409863454720000 |
| 17 | 25152557411534192640000 |