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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 5 |
| 5 | 12 |
| 6 | 33 |
| 7 | 139 |
| 8 | 1251 |
| 9 | 10598 |
| 10 | 176642 |
| 11 | 4720781 |
| 12 | 106779821 |
| 13 | 5953841083 |
| 14 | 373265833332 |
| 15 | 23827795512789 |
| 16 | 3914313805097976 |
| 17 | 548326897932632059 |
| 18 | 108647952177920032693 |
| 19 | 45931050219457726501030 |
| 20 | 14741338951262398648743248 |
| 21 | 9489791738688118291360645939 |
[1,1,2,3,5,12,33,139,1251,10598,176642,4720781, 106779821,5953841083,373265833332,23827795512789, 3914313805097976,548326897932632059, 108647952177920032693,45931050219457726501030, 14741338951262398648743248, 9489791738688118291360645939] |