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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 16 |
| 6 | 37 |
| 7 | 80 |
| 8 | 172 |
| 9 | 377 |
| 10 | 839 |
| 11 | 1874 |
| 12 | 4175 |
| 13 | 9274 |
| 14 | 20577 |
| 15 | 45665 |
| 16 | 101393 |
| 17 | 225193 |
| 18 | 500162 |
| 19 | 1110790 |
| 20 | 2466760 |
| 21 | 5477917 |
| 22 | 12164896 |
| 23 | 27015092 |
| 24 | 59993817 |
| 25 | 133231279 |
| 26 | 295872778 |
| 27 | 657057431 |
| 28 | 1459155634 |
| 29 | 3240410561 |
| 30 | 7196122817 |
[1,1,1,2,6,16,37,80,172,377,839,1874,4175,9274, 20577,45665,101393,225193,500162,1110790,2466760, 5477917,12164896,27015092,59993817,133231279, 295872778,657057431,1459155634,3240410561, 7196122817] |