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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 13 |
| 6 | 39 |
| 7 | 147 |
| 8 | 755 |
| 9 | 5230 |
| 10 | 50282 |
| 11 | 677730 |
| 12 | 13010007 |
| 13 | 359551127 |
| 14 | 14457741910 |
| 15 | 853120090801 |
| 16 | 74437567936635 |
| 17 | 9666377127590346 |
| 18 | 1878877762201043122 |
| 19 | 549363336929733878734 |
| 20 | 242695457366120511255070 |
| 21 | 16263199149257162654631846 |
[1,2,3,6,13,39,147,755,5230,50282,677730,13010007, 359551127,14457741910,853120090801,74437567936635, 9666377127590346,1878877762201043122, 549363336929733878734,242695457366120511255070, 16263199149257162654631846] |