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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 43 |
| 6 | 140 |
| 7 | 474 |
| 8 | 1648 |
| 9 | 5839 |
| 10 | 20980 |
| 11 | 76202 |
| 12 | 279168 |
| 13 | 1029962 |
| 14 | 3822336 |
| 15 | 14256228 |
| 16 | 53400912 |
[1,1,2,5,14,43,140,474,1648,5839,20980,76202, 279168,1029962,3822336,14256228,53400912] |