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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 7 |
| 5 | 16 |
| 6 | 43 |
| 7 | 89 |
| 8 | 216 |
| 9 | 502 |
| 10 | 1154 |
| 11 | 2715 |
| 12 | 6268 |
| 13 | 14583 |
| 14 | 33936 |
| 15 | 78787 |
| 16 | 183141 |
| 17 | 425547 |
| 18 | 988765 |
| 19 | 2297533 |
| 20 | 5338321 |
| 21 | 12403697 |
| 22 | 28819646 |
| 23 | 66962219 |
| 24 | 155583912 |
| 25 | 361492693 |
| 26 | 839915741 |
| 27 | 1951499287 |
| 28 | 4534218339 |
| 29 | 10535031491 |
| 30 | 24477592379 |
[1,1,1,4,7,16,43,89,216,502,1154,2715,6268,14583, 33936,78787,183141,425547,988765,2297533,5338321, 12403697,28819646,66962219,155583912,361492693, 839915741,1951499287,4534218339,10535031491, 24477592379] |