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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 7 |
| 4 | 60 |
| 5 | 519 |
| 6 | 5890 |
| 7 | 76637 |
| 8 | 1158808 |
| 9 | 19770383 |
| 10 | 377036646 |
| 11 | 7939301349 |
| 12 | 183033429524 |
| 13 | 4584731740471 |
| 14 | 123994410402122 |
| 15 | 3601004174824573 |
| 16 | 111771076844177328 |
| 17 | 3692510526181175583 |
| 18 | 129364120799128910158 |
| 19 | 4790645026641043053269 |
| 20 | 186981399898552187792620 |
[1,0,2,7,60,519,5890,76637,1158808,19770383, 377036646,7939301349,183033429524,4584731740471, 123994410402122,3601004174824573, 111771076844177328,3692510526181175583, 129364120799128910158,4790645026641043053269, 186981399898552187792620] |