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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 247 |
| 4 | 4065 |
| 5 | 85491 |
| 6 | 2182693 |
| 7 | 65442231 |
| 8 | 2250974337 |
| 9 | 87294730915 |
| 10 | 3765990774261 |
| 11 | 178812764864823 |
| 12 | 9263097025165921 |
| 13 | 519758109395523987 |
| 14 | 31395814449356220165 |
| 15 | 2030900829581042821111 |
| 16 | 140048613574000341166593 |
| 17 | 10254546115119932443226691 |
| 18 | 794473964275576023742250197 |
[1,3,21,247,4065,85491,2182693,65442231, 2250974337,87294730915,3765990774261, 178812764864823,9263097025165921, 519758109395523987,31395814449356220165, 2030900829581042821111,140048613574000341166593, 10254546115119932443226691, 794473964275576023742250197] |