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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 50 |
| 4 | 1225 |
| 5 | 7938 |
| 6 | 106722 |
| 7 | 736164 |
| 8 | 41409225 |
| 9 | 295488050 |
| 10 | 4266847442 |
| 11 | 31102144164 |
| 12 | 914057459042 |
| 13 | 6760780022500 |
| 14 | 100583849722500 |
| 15 | 751920156592200 |
| 16 | 90324408810638025 |
| 17 | 680714748752836050 |
| 18 | 10294760089163261250 |
| 19 | 78080479568224402500 |
| 20 | 2375208188465386324050 |
[1,1,9,50,1225,7938,106722,736164,41409225, 295488050,4266847442,31102144164,914057459042, 6760780022500,100583849722500,751920156592200, 90324408810638025,680714748752836050, 10294760089163261250,78080479568224402500, 2375208188465386324050] |