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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 51 |
| 5 | 325 |
| 6 | 2222 |
| 7 | 15926 |
| 8 | 118085 |
| 9 | 898217 |
| 10 | 6970053 |
| 11 | 54960439 |
| 12 | 439112322 |
| 13 | 3547096393 |
| 14 | 28921270773 |
| 15 | 237704587991 |
| 16 | 1967321998468 |
| 17 | 16381661824340 |
| 18 | 137144132047520 |
| 19 | 1153655788549216 |
| 20 | 9746264972136632 |
| 21 | 82656795697147384 |
| 22 | 703459159019830315 |
| 23 | 6005956718852682504 |
| 24 | 51426768620398474939 |
[1,2,9,51,325,2222,15926,118085,898217,6970053, 54960439,439112322,3547096393,28921270773, 237704587991,1967321998468,16381661824340, 137144132047520,1153655788549216,9746264972136632, 82656795697147384,703459159019830315, 6005956718852682504,51426768620398474939] |