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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 21 |
| 4 | 119 |
| 5 | 703 |
| 6 | 4515 |
| 7 | 30227 |
| 8 | 210274 |
| 9 | 1503930 |
| 10 | 11008198 |
| 11 | 82099262 |
| 12 | 622013122 |
| 13 | 4775754930 |
| 14 | 37089503826 |
| 15 | 290914775618 |
| 16 | 2301706690657 |
| 17 | 18351027768401 |
| 18 | 147308337621061 |
| 19 | 1189704370416949 |
| 20 | 9661185599013209 |
| 21 | 78844977025403657 |
[1,1,5,21,119,703,4515,30227,210274,1503930, 11008198,82099262,622013122,4775754930, 37089503826,290914775618,2301706690657, 18351027768401,147308337621061,1189704370416949, 9661185599013209,78844977025403657] |