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 | 3 |
| 3 | 12 |
| 4 | 60 |
| 5 | 420 |
| 6 | 3780 |
| 7 | 41580 |
| 8 | 540540 |
| 9 | 8648640 |
| 10 | 147026880 |
| 11 | 2793510720 |
| 12 | 64250746560 |
| 13 | 1606268664000 |
| 14 | 46581791256000 |
| 15 | 1444035528936000 |
| 16 | 53429314570632000 |
| 17 | 2190601897395912000 |
| 18 | 94195881588024216000 |
| 19 | 4427206434637138152000 |
| 20 | 216933115297219769448000 |
| 21 | 11497455110752647780744000 |