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 | 48 |
| 4 | 1566 |
| 5 | 126120 |
| 6 | 18153720 |
| 7 | 4357332000 |
| 8 | 1619499374640 |
| 9 | 883124275824000 |
| 10 | 677267024315091840 |
| 11 | 706022078404964428800 |
| 12 | 972890835488032591468800 |
| 13 | 1731258722423272253052441600 |
| 14 | 3900512495412914495014418918400 |
| 15 | 10938873545450798558110852249497600 |