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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 20 |
| 5 | 44 |
| 6 | 96 |
| 7 | 209 |
| 8 | 455 |
| 9 | 991 |
| 10 | 2159 |
| 11 | 4704 |
| 12 | 10249 |
| 13 | 22330 |
| 14 | 48651 |
| 15 | 105997 |
| 16 | 230938 |
| 17 | 503150 |
| 18 | 1096225 |
| 19 | 2388372 |
| 20 | 5203604 |
| 21 | 11337218 |
| 22 | 24700671 |
| 23 | 53815949 |
| 24 | 117250109 |
| 25 | 255455647 |
| 26 | 556567394 |
| 27 | 1212606837 |
| 28 | 2641935832 |
| 29 | 5756049469 |
| 30 | 12540844137 |
[1,2,4,9,20,44,96,209,455,991,2159,4704,10249, 22330,48651,105997,230938,503150,1096225,2388372, 5203604,11337218,24700671,53815949,117250109, 255455647,556567394,1212606837,2641935832, 5756049469,12540844137] |