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 | 420 |
| 3 | 201600 |
| 4 | 264264000 |
| 5 | 734557824000 |
| 6 | 3723191087616000 |
| 7 | 31125877492469760000 |
| 8 | 399532678960326912000000 |
| 9 | 7462849882264211635200000000 |
| 10 | 194563959280510261541299200000000 |
| 11 | 6847568575944052279580806348800000000 |
| 12 | 316573366618757452963440048714547200000000 |