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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 20 |
| 3 | 543 |
| 4 | 22096 |
| 5 | 1304045 |
| 6 | 106478916 |
| 7 | 11545342795 |
| 8 | 1608000044288 |
| 9 | 280061940550041 |
| 10 | 59677171216017940 |
| 11 | 15278632095285640631 |
| 12 | 4628964787172536267920 |
| 13 | 1638318264614752659427333 |
| 14 | 669895681115518466689138436 |
| 15 | 313418973409285344224352078435 |
[0,1,20,543,22096,1304045,106478916,11545342795, 1608000044288,280061940550041,59677171216017940, 15278632095285640631,4628964787172536267920, 1638318264614752659427333, 669895681115518466689138436, 313418973409285344224352078435] |