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 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 72 |
| 6 | 390 |
| 7 | 2880 |
| 8 | 21672 |
| 9 | 201600 |
| 10 | 1935360 |
| 11 | 21772800 |
| 12 | 253756800 |
| 13 | 3353011200 |
| 14 | 45924278400 |