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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 86 |
| 5 | 647 |
| 6 | 5739 |
| 7 | 58647 |
| 8 | 679513 |
| 9 | 8818219 |
| 10 | 126887789 |
| 11 | 2007051456 |
| 12 | 34634864692 |
| 13 | 647737588429 |
| 14 | 13052029344893 |
| 15 | 281915983915202 |
| 16 | 6497718168838214 |
| 17 | 159172833649907801 |
| 18 | 4129605445474716345 |
| 19 | 113112957674428539930 |
| 20 | 3261790879443599064394 |
| 21 | 98772906841120521388973 |
[1,1,3,14,86,647,5739,58647,679513,8818219, 126887789,2007051456,34634864692,647737588429, 13052029344893,281915983915202,6497718168838214, 159172833649907801,4129605445474716345, 113112957674428539930,3261790879443599064394, 98772906841120521388973] |