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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 10 |
| 4 | 64 |
| 5 | 874 |
| 6 | 11602 |
| 7 | 214696 |
| 8 | 4287376 |
| 9 | 102791944 |
| 10 | 2706467608 |
| 11 | 80520419440 |
| 12 | 2616373545040 |
| 13 | 93309672227680 |
| 14 | 3598524149027680 |
| 15 | 149819807423180800 |
| 16 | 6681701058862660480 |
| 17 | 318224146460638476160 |
| 18 | 16106859257541255648640 |
| 19 | 863764371283534316220160 |
[1,1,1,10,64,874,11602,214696,4287376,102791944, 2706467608,80520419440,2616373545040, 93309672227680,3598524149027680, 149819807423180800,6681701058862660480, 318224146460638476160,16106859257541255648640, 863764371283534316220160] |