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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 50 |
| 5 | 426 |
| 6 | 4606 |
| 7 | 60418 |
| 8 | 932282 |
| 9 | 16547562 |
| 10 | 332152614 |
| 11 | 7439791314 |
| 12 | 183964790514 |
| 13 | 4977606096570 |
| 14 | 146287199495310 |
| 15 | 4640510332052370 |
| 16 | 158035939351814250 |
| 17 | 5750979655319685834 |
| 18 | 222710142933114209526 |
| 19 | 9144799526131421284434 |
| 20 | 396863889188887568805282 |
[1,1,2,8,50,426,4606,60418,932282,16547562, 332152614,7439791314,183964790514,4977606096570, 146287199495310,4640510332052370, 158035939351814250,5750979655319685834, 222710142933114209526,9144799526131421284434, 396863889188887568805282] |