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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 48 |
| 8 | 114 |
| 9 | 282 |
| 10 | 701 |
| 11 | 1763 |
| 12 | 4438 |
| 13 | 11212 |
| 14 | 28287 |
| 15 | 71357 |
| 16 | 179696 |
| 17 | 451946 |
| 18 | 1134720 |
| 19 | 2844954 |
| 20 | 7122041 |
| 21 | 17805884 |
| 22 | 44459523 |
| 23 | 110882964 |
| 24 | 276241029 |
| 25 | 687501846 |
| 26 | 1709406423 |
| 27 | 4246490811 |
| 28 | 10540185493 |
| 29 | 26140852721 |
| 30 | 64782959403 |
[1,1,1,2,4,9,20,48,114,282,701,1763,4438,11212, 28287,71357,179696,451946,1134720,2844954,7122041, 17805884,44459523,110882964,276241029,687501846, 1709406423,4246490811,10540185493,26140852721, 64782959403] |