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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 19 |
| 5 | 52 |
| 6 | 151 |
| 7 | 442 |
| 8 | 1314 |
| 9 | 3921 |
| 10 | 11737 |
| 11 | 35171 |
| 12 | 105464 |
| 13 | 316318 |
| 14 | 948863 |
| 15 | 2846461 |
| 16 | 8539221 |
| 17 | 25617443 |
| 18 | 76852054 |
| 19 | 230555794 |
| 20 | 691666924 |
| 21 | 2075000173 |
| 22 | 6224999772 |
| 23 | 18674998357 |
| 24 | 56024993883 |
| 25 | 168074980137 |
| 26 | 504224938548 |
| 27 | 1512674813304 |
| 28 | 4538024437036 |
[1,1,3,7,19,52,151,442,1314,3921,11737,35171, 105464,316318,948863,2846461,8539221,25617443, 76852054,230555794,691666924,2075000173, 6224999772,18674998357,56024993883,168074980137, 504224938548,1512674813304,4538024437036] |