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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 51 |
| 3 | 450 |
| 4 | 4095 |
| 5 | 37908 |
| 6 | 354978 |
| 7 | 3351348 |
| 8 | 31833945 |
| 9 | 303822090 |
| 10 | 2910657321 |
| 11 | 27970777926 |
| 12 | 269484894081 |
| 13 | 2602002636540 |
| 14 | 25170322256010 |
| 15 | 243876058527132 |
| 16 | 2366251795228437 |
| 17 | 22987502934573762 |
| 18 | 223563791480714685 |
| 19 | 2176402892261301990 |
| 20 | 21206170582394740371 |
[1,6,51,450,4095,37908,354978,3351348,31833945, 303822090,2910657321,27970777926,269484894081, 2602002636540,25170322256010,243876058527132, 2366251795228437,22987502934573762, 223563791480714685,2176402892261301990, 21206170582394740371] |