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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 102 |
| 4 | 807 |
| 5 | 6951 |
| 6 | 63240 |
| 7 | 597864 |
| 8 | 5815167 |
| 9 | 57815553 |
| 10 | 584919951 |
| 11 | 6002197914 |
| 12 | 62321630100 |
| 13 | 653553174756 |
| 14 | 6912106219176 |
| 15 | 73642451396160 |
| 16 | 789642274208271 |
| 17 | 8515008918555573 |
| 18 | 92281921130853213 |
| 19 | 1004600177464845450 |
| 20 | 10980406558088695599 |
| 21 | 120454756647900759543 |
[1,3,15,102,807,6951,63240,597864,5815167, 57815553,584919951,6002197914,62321630100, 653553174756,6912106219176,73642451396160, 789642274208271,8515008918555573, 92281921130853213,1004600177464845450, 10980406558088695599,120454756647900759543] |