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 | 72 |
| 3 | 648 |
| 4 | 5184 |
| 5 | 38880 |
| 6 | 279936 |
| 7 | 1959552 |
| 8 | 13436928 |
| 9 | 90699264 |
| 10 | 604661760 |
| 11 | 3990767616 |
| 12 | 26121388032 |
| 13 | 169789022208 |
| 14 | 1097098297344 |
| 15 | 7052774768640 |
| 16 | 45137758519296 |
| 17 | 287753210560512 |
| 18 | 1828079220031488 |
| 19 | 11577835060199424 |
| 20 | 73123168801259520 |
| 21 | 460675963447934976 |