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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 20 |
| 5 | 47 |
| 6 | 103 |
| 7 | 198 |
| 8 | 512 |
| 9 | 1161 |
| 10 | 1985 |
| 11 | 5590 |
| 12 | 13005 |
| 13 | 21684 |
| 14 | 59294 |
| 15 | 142273 |
| 16 | 270858 |
| 17 | 634187 |
| 18 | 1526399 |
| 19 | 3256372 |
| 20 | 6779657 |
| 21 | 16020364 |
| 22 | 37758202 |
| 23 | 79702477 |
| 24 | 164647757 |
| 25 | 424655100 |
| 26 | 940639154 |
| 27 | 1709638551 |
| 28 | 4675803604 |
| 29 | 10774789429 |
[1,2,4,9,20,47,103,198,512,1161,1985,5590,13005, 21684,59294,142273,270858,634187,1526399,3256372, 6779657,16020364,37758202,79702477,164647757, 424655100,940639154,1709638551,4675803604, 10774789429] |