| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 56 |
| 3 | 2448 |
| 4 | 379168 |
| 5 | 223096896 |
| 6 | 514098000000 |
| 7 | 4691436926959872 |
| 8 | 170097530401558168064 |
| 9 | 24520599890836361905701888 |
| 10 | 14055963692387060312500000000000 |
[1,4,56,2448,379168,223096896,514098000000, 4691436926959872,170097530401558168064, 24520599890836361905701888, 14055963692387060312500000000000] |