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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 4 |
| 5 | 15 |
| 6 | 22 |
| 7 | 91 |
| 8 | 140 |
| 9 | 612 |
| 10 | 969 |
| 11 | 4389 |
| 12 | 7084 |
| 13 | 32890 |
| 14 | 53820 |
| 15 | 254475 |
| 16 | 420732 |
| 17 | 2017356 |
| 18 | 3362260 |
| 19 | 16301164 |
| 20 | 27343888 |
| 21 | 133767543 |
| 22 | 225568798 |
| 23 | 1111731933 |
| 24 | 1882933364 |
| 25 | 9338434700 |
| 26 | 15875338990 |
| 27 | 79155435870 |
| 28 | 134993766600 |
| 29 | 676196049060 |
| 30 | 1156393243320 |
| 31 | 5815796869995 |
[1,1,1,3,4,15,22,91,140,612,969,4389,7084,32890, 53820,254475,420732,2017356,3362260,16301164, 27343888,133767543,225568798,1111731933, 1882933364,9338434700,15875338990,79155435870, 134993766600,676196049060,1156393243320, 5815796869995] |