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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 7 |
| 3 | 44 |
| 4 | 274 |
| 5 | 1705 |
| 6 | 10609 |
| 7 | 66012 |
| 8 | 410744 |
| 9 | 2555757 |
| 10 | 15902591 |
| 11 | 98950096 |
| 12 | 615693474 |
| 13 | 3831006429 |
| 14 | 23837527729 |
| 15 | 148323355432 |
| 16 | 922906855808 |
| 17 | 5742568741225 |
| 18 | 35731770264967 |
| 19 | 222332455004452 |
| 20 | 1383410902447554 |
| 21 | 8607945812375585 |
| 22 | 53560898629395777 |
| 23 | 333269972246340068 |
[0,1,7,44,274,1705,10609,66012,410744,2555757, 15902591,98950096,615693474,3831006429, 23837527729,148323355432,922906855808, 5742568741225,35731770264967,222332455004452, 1383410902447554,8607945812375585, 53560898629395777,333269972246340068] |