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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 4 |
| 4 | 21 |
| 5 | 168 |
| 6 | 10754 |
| 7 | 25461498 |
| 8 | 105205312405537 |
| 9 | 2273436544813042470905435068 |
| 10 | 580632014636885174037652548241171956049642213022500047 |
| 11 | 105076738483143967759563061000636154401568577693011463452250666394865203888381724797435152416096091560375615 |
[2,2,4,21,168,10754,25461498,105205312405537, 2273436544813042470905435068, 58063201463688517403765254824117195604964221302250\ 0047, 10507673848314396775956306100063615440156857769301\ 14634522506663948652038883817247974351524160960915\ 60375615] |