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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 16 |
| 7 | 45 |
| 8 | 128 |
| 9 | 371 |
| 10 | 1106 |
| 11 | 3343 |
| 12 | 10230 |
| 13 | 31635 |
| 14 | 98714 |
| 15 | 310366 |
| 16 | 982437 |
| 17 | 3128051 |
| 18 | 10011848 |
| 19 | 32193840 |
| 20 | 103955571 |
| 21 | 336946034 |
| 22 | 1095873115 |
| 23 | 3575319049 |
| 24 | 11697938232 |
| 25 | 38374479841 |
| 26 | 126190075741 |
| 27 | 415889689954 |
| 28 | 1373506798548 |
[1,1,1,3,6,16,45,128,371,1106,3343,10230,31635, 98714,310366,982437,3128051,10011848,32193840, 103955571,336946034,1095873115,3575319049, 11697938232,38374479841,126190075741,415889689954, 1373506798548] |