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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 40 |
| 5 | 315 |
| 6 | 2908 |
| 7 | 30989 |
| 8 | 375611 |
| 9 | 5112570 |
| 10 | 77305024 |
| 11 | 1286640410 |
| 12 | 23387713930 |
| 13 | 461187042992 |
| 14 | 9808283703684 |
| 15 | 223833267479764 |
| 16 | 5456669750439788 |
| 17 | 141540592345674800 |
| 18 | 3892707724320135616 |
| 19 | 113153294901088030320 |
| 20 | 3466501398608272647984 |
| 21 | 111636571036702743967104 |
| 22 | 3770483138507706753943584 |
[1,6,40,315,2908,30989,375611,5112570,77305024, 1286640410,23387713930,461187042992,9808283703684, 223833267479764,5456669750439788, 141540592345674800,3892707724320135616, 113153294901088030320,3466501398608272647984, 111636571036702743967104, 3770483138507706753943584] |