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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 6 |
| 4 | 11 |
| 5 | 24 |
| 6 | 52 |
| 7 | 112 |
| 8 | 251 |
| 9 | 574 |
| 10 | 1347 |
| 11 | 3242 |
| 12 | 7996 |
| 13 | 20202 |
| 14 | 52245 |
| 15 | 138200 |
| 16 | 373640 |
| 17 | 1031702 |
| 18 | 2907207 |
| 19 | 8353892 |
| 20 | 24460864 |
| 21 | 72931232 |
| 22 | 221265823 |
| 23 | 682632254 |
| 24 | 2140211338 |
| 25 | 6814954528 |
| 26 | 22027143227 |
| 27 | 72228405060 |
| 28 | 240154754720 |
[1,2,3,6,11,24,52,112,251,574,1347,3242,7996, 20202,52245,138200,373640,1031702,2907207,8353892, 24460864,72931232,221265823,682632254,2140211338, 6814954528,22027143227,72228405060,240154754720] |