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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 12 |
| 7 | 34 |
| 8 | 120 |
| 9 | 412 |
| 10 | 1608 |
| 11 | 6244 |
| 12 | 26288 |
| 13 | 111448 |
| 14 | 499256 |
| 15 | 2265288 |
| 16 | 10701896 |
| 17 | 51339768 |
| 18 | 254175048 |
| 19 | 1278947304 |
| 20 | 6604214760 |
| 21 | 34662182904 |
| 22 | 186002333640 |
| 23 | 1014140252376 |
| 24 | 5638617162312 |
| 25 | 31837193871480 |
| 26 | 182962292354376 |
| 27 | 1067120997002680 |
| 28 | 6325487157903240 |
| 29 | 38030207563538680 |
[1,1,1,1,2,4,12,34,120,412,1608,6244,26288,111448, 499256,2265288,10701896,51339768,254175048, 1278947304,6604214760,34662182904,186002333640, 1014140252376,5638617162312,31837193871480, 182962292354376,1067120997002680,6325487157903240, 38030207563538680] |