| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 56 |
| 5 | 408 |
| 6 | 4608 |
| 7 | 80784 |
| 8 | 2201536 |
| 9 | 93224736 |
| 10 | 6134017792 |
| 11 | 627029574336 |
| 12 | 99602689462784 |
| 13 | 24580813373119872 |
| 14 | 9426621978735869952 |
| 15 | 5616371724370667073792 |
| 16 | 5199854362208758062125056 |
| 17 | 7479400854548558531507839488 |
| 18 | 16717751433807850998823619411968 |
[1,2,4,12,56,408,4608,80784,2201536,93224736, 6134017792,627029574336,99602689462784, 24580813373119872,9426621978735869952, 5616371724370667073792,5199854362208758062125056, 7479400854548558531507839488, 16717751433807850998823619411968] |