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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 36 |
| 5 | 150 |
| 6 | 2340 |
| 7 | 47166 |
| 8 | 676116 |
| 9 | 10602150 |
| 10 | 248197860 |
| 11 | 6304530606 |
| 12 | 154511054676 |
| 13 | 4227889233750 |
| 14 | 134462460901860 |
| 15 | 4519745455581726 |
| 16 | 157756124072317716 |
| 17 | 5960350758700381830 |
| 18 | 243292987180534250340 |
| 19 | 10433760831781705395726 |
| 20 | 469420864688765414084436 |
[1,0,0,6,36,150,2340,47166,676116,10602150, 248197860,6304530606,154511054676,4227889233750, 134462460901860,4519745455581726, 157756124072317716,5960350758700381830, 243292987180534250340,10433760831781705395726, 469420864688765414084436] |