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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 16 |
| 6 | 96 |
| 7 | 5184 |
| 8 | 829440 |
| 9 | 1911029760 |
| 10 | 13002646487040 |
| 11 | 10065920762063093760 |
| 12 | 9319918463639717615448883200 |
| 13 | 137422208150223932126848386360776224407552000 |
[1,2,2,4,16,96,5184,829440,1911029760, 13002646487040,10065920762063093760, 9319918463639717615448883200, 137422208150223932126848386360776224407552000] |