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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 11 |
| 3 | 55 |
| 4 | 309 |
| 5 | 1931 |
| 6 | 13543 |
| 7 | 101991 |
| 8 | 828425 |
| 9 | 7192819 |
| 10 | 66002691 |
| 11 | 639830423 |
| 12 | 6510397501 |
| 13 | 69266297595 |
| 14 | 768989536799 |
| 15 | 8876171274631 |
| 16 | 106301772962193 |
| 17 | 1318277355041891 |
| 18 | 16892429768517115 |
| 19 | 223330116792810999 |
| 20 | 3041570471301007301 |
| 21 | 42611228176879105003 |
[1,3,11,55,309,1931,13543,101991,828425,7192819, 66002691,639830423,6510397501,69266297595, 768989536799,8876171274631,106301772962193, 1318277355041891,16892429768517115, 223330116792810999,3041570471301007301, 42611228176879105003] |