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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 30 |
| 6 | 240 |
| 7 | 140 |
| 8 | 840 |
| 9 | 3780 |
| 10 | 15120 |
| 11 | 2772 |
| 12 | 221760 |
| 13 | 12012 |
| 14 | 960960 |
| 15 | 9266400 |
| 16 | 10810800 |
| 17 | 218790 |
| 18 | 7351344000 |
| 19 | 923780 |
| 20 | 16761064320 |
| 21 | 3259095840 |
| 22 | 3910915008 |
| 23 | 16224936 |
| 24 | 41977154419200 |
| 25 | 2028117000 |
| 26 | 249864014400 |