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) |
|---|---|
| 2 | 1 |
| 3 | 12 |
| 4 | 56 |
| 5 | 480 |
| 6 | 2040 |
| 7 | 16576 |
| 8 | 69888 |
| 9 | 557568 |
| 10 | 2361600 |
| 11 | 18675712 |
| 12 | 79613952 |
| 13 | 626409472 |
| 14 | 2686867456 |
| 15 | 21071708160 |
| 16 | 90875494400 |
| 17 | 711081984000 |
| 18 | 3081088991232 |
| 19 | 24069137760256 |
| 20 | 104712901754880 |
| 21 | 816979824869376 |
| 22 | 3566715303624704 |
| 23 | 27800440481513472 |
| 24 | 121738713372819456 |
| 25 | 948129286114508800 |