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 | 6 |
| 2 | 84 |
| 3 | 780 |
| 4 | 5880 |
| 5 | 39060 |
| 6 | 238392 |
| 7 | 1369368 |
| 8 | 7516080 |
| 9 | 39819780 |
| 10 | 205079160 |
| 11 | 1032047016 |
| 12 | 5094629904 |
| 13 | 24743027400 |
| 14 | 118504436400 |
| 15 | 560749834800 |
| 16 | 2625519143520 |
| 17 | 12179090862180 |
| 18 | 56029885342200 |
| 19 | 255864364648200 |