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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 71 |
| 5 | 235 |
| 6 | 1147 |
| 7 | 4261 |
| 8 | 20885 |
| 9 | 81049 |
| 10 | 399677 |
| 11 | 1609593 |
| 12 | 7961105 |
| 13 | 32824569 |
| 14 | 162734865 |
| 15 | 683496555 |
| 16 | 3394132835 |
| 17 | 14457881135 |
| 18 | 71884823559 |
| 19 | 309701765151 |
| 20 | 1541308824347 |
| 21 | 6702318246579 |
| 22 | 33380693562987 |
| 23 | 146283366386803 |
| 24 | 728994078707843 |
| 25 | 3215695886993247 |
| 26 | 16032946387905691 |
| 27 | 71123532628247839 |
[1,1,5,15,71,235,1147,4261,20885,81049,399677, 1609593,7961105,32824569,162734865,683496555, 3394132835,14457881135,71884823559,309701765151, 1541308824347,6702318246579,33380693562987, 146283366386803,728994078707843,3215695886993247, 16032946387905691,71123532628247839] |