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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 10 |
| 6 | 25 |
| 7 | 68 |
| 8 | 187 |
| 9 | 530 |
| 10 | 1523 |
| 11 | 4447 |
| 12 | 13121 |
| 13 | 39107 |
| 14 | 117490 |
| 15 | 355507 |
| 16 | 1082234 |
| 17 | 3312255 |
| 18 | 10185125 |
| 19 | 31450633 |
| 20 | 97480337 |
| 21 | 303157086 |
| 22 | 945671951 |
| 23 | 2958113722 |
| 24 | 9276528602 |
| 25 | 29158191215 |
| 26 | 91845796986 |
| 27 | 289874628176 |
| 28 | 916536727561 |
[1,1,2,4,10,25,68,187,530,1523,4447,13121,39107, 117490,355507,1082234,3312255,10185125,31450633, 97480337,303157086,945671951,2958113722, 9276528602,29158191215,91845796986,289874628176, 916536727561] |