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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 110 |
| 5 | 986 |
| 6 | 10202 |
| 7 | 126288 |
| 8 | 1770120 |
| 9 | 27939192 |
| 10 | 489658632 |
| 11 | 9455296896 |
| 12 | 198951693360 |
| 13 | 4537680805776 |
| 14 | 111426422418768 |
| 15 | 2931467216681856 |
| 16 | 82273083792879744 |
| 17 | 2453340521239749504 |
| 18 | 77458777017799833216 |
| 19 | 2581489882182061744128 |
[1,1,3,16,110,986,10202,126288,1770120,27939192, 489658632,9455296896,198951693360,4537680805776, 111426422418768,2931467216681856, 82273083792879744,2453340521239749504, 77458777017799833216,2581489882182061744128] |