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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 77 |
| 6 | 283 |
| 7 | 1032 |
| 8 | 3740 |
| 9 | 13522 |
| 10 | 48930 |
| 11 | 177564 |
| 12 | 646908 |
| 13 | 2367121 |
| 14 | 8699706 |
| 15 | 32108614 |
| 16 | 118975273 |
| 17 | 442467434 |
| 18 | 1651076429 |
| 19 | 6180073782 |
| 20 | 23197995681 |
| 21 | 87304824502 |
| 22 | 329357941951 |
| 23 | 1245262325246 |
| 24 | 4717865597299 |
| 25 | 17908489016748 |
| 26 | 68099538024617 |
| 27 | 259388123347450 |
| 28 | 989533568712759 |
[1,1,2,6,21,77,283,1032,3740,13522,48930,177564, 646908,2367121,8699706,32108614,118975273, 442467434,1651076429,6180073782,23197995681, 87304824502,329357941951,1245262325246, 4717865597299,17908489016748,68099538024617, 259388123347450,989533568712759] |