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 | 1 |
| 1 | 4 |
| 2 | 104 |
| 3 | 6880 |
| 4 | 855680 |
| 5 | 171673600 |
| 6 | 50628300800 |
| 7 | 20616410214400 |
| 8 | 11081874771968000 |
| 9 | 7600553402810368000 |
| 10 | 6477130108444835840000 |
| 11 | 6713789344917138964480000 |
| 12 | 8317650472128427128258560000 |
| 13 | 12137529532422860667092992000000 |