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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 11 |
| 4 | 41 |
| 5 | 199 |
| 6 | 1184 |
| 7 | 8273 |
| 8 | 66163 |
| 9 | 595439 |
| 10 | 5954354 |
| 11 | 65497849 |
| 12 | 785974133 |
| 13 | 10217663663 |
| 14 | 143047291204 |
| 15 | 2145709367969 |
| 16 | 34331349887399 |
| 17 | 583632948085663 |
| 18 | 10505393065541798 |
| 19 | 199602468245294009 |
| 20 | 3992049364905880009 |
| 21 | 83833036663023479999 |
[2,4,11,41,199,1184,8273,66163,595439,5954354, 65497849,785974133,10217663663,143047291204, 2145709367969,34331349887399,583632948085663, 10505393065541798,199602468245294009, 3992049364905880009,83833036663023479999] |