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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 87 |
| 5 | 344 |
| 6 | 1430 |
| 7 | 6006 |
| 8 | 25638 |
| 9 | 111108 |
| 10 | 485979 |
| 11 | 2144374 |
| 12 | 9526239 |
| 13 | 42581108 |
| 14 | 191357708 |
| 15 | 863551551 |
| 16 | 3912874126 |
| 17 | 17792811362 |
| 18 | 81149740528 |
| 19 | 371155976937 |
| 20 | 1701830597050 |
| 21 | 7820751344589 |
| 22 | 36014935517232 |
| 23 | 166162951039617 |
| 24 | 767957329992987 |
| 25 | 3554955243640582 |
| 26 | 16480495255912614 |
| 27 | 76507069324161891 |
[1,2,6,23,87,344,1430,6006,25638,111108,485979, 2144374,9526239,42581108,191357708,863551551, 3912874126,17792811362,81149740528,371155976937, 1701830597050,7820751344589,36014935517232, 166162951039617,767957329992987,3554955243640582, 16480495255912614,76507069324161891] |