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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 24 |
| 3 | 143 |
| 4 | 1130 |
| 5 | 7808 |
| 6 | 57265 |
| 7 | 403872 |
| 8 | 2873739 |
| 9 | 20432891 |
| 10 | 144677017 |
| 11 | 1026964990 |
| 12 | 7278200770 |
| 13 | 51599366898 |
| 14 | 365810734012 |
| 15 | 2592996883759 |
| 16 | 18381778773564 |
| 17 | 130301190621786 |
| 18 | 923665265649234 |
| 19 | 6547577009509537 |
| 20 | 46413487626522921 |
[2,24,143,1130,7808,57265,403872,2873739,20432891, 144677017,1026964990,7278200770,51599366898, 365810734012,2592996883759,18381778773564, 130301190621786,923665265649234,6547577009509537, 46413487626522921] |