| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 64 |
| 3 | 2304 |
| 4 | 147456 |
| 5 | 14745600 |
| 6 | 2123366400 |
| 7 | 416179814400 |
| 8 | 106542032486400 |
| 9 | 34519618525593600 |
| 10 | 13807847410237440000 |
| 11 | 6682998146554920960000 |
| 12 | 3849406932415634472960000 |
| 13 | 2602199086312968903720960000 |
| 14 | 2040124083669367620517232640000 |
[1,4,64,2304,147456,14745600,2123366400, 416179814400,106542032486400,34519618525593600, 13807847410237440000,6682998146554920960000, 3849406932415634472960000, 2602199086312968903720960000, 2040124083669367620517232640000] |