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 | 0 |
| 2 | 12 |
| 3 | 396 |
| 4 | 21672 |
| 5 | 1918920 |
| 6 | 250696980 |
| 7 | 45304472052 |
| 8 | 10816917169296 |
| 9 | 3296928965854032 |
| 10 | 1248938916843586140 |
| 11 | 575559130836761023260 |
| 12 | 317049200473798671358392 |
| 13 | 205722831410326997504441496 |
| 14 | 155295648728262284680608862692 |
| 15 | 134934407215203512994225979686660 |