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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 27 |
| 4 | 254 |
| 5 | 2301 |
| 6 | 19053 |
| 7 | 149696 |
| 8 | 1124969 |
| 9 | 8178511 |
| 10 | 57898166 |
| 11 | 401186545 |
| 12 | 2731110793 |
| 13 | 18318459744 |
| 14 | 121328163101 |
| 15 | 794920836163 |
| 16 | 5159325575790 |
| 17 | 33210311871861 |
| 18 | 212217346520565 |
| 19 | 1347303236328128 |
| 20 | 8503951716838241 |
[0,3,27,254,2301,19053,149696,1124969,8178511, 57898166,401186545,2731110793,18318459744, 121328163101,794920836163,5159325575790, 33210311871861,212217346520565,1347303236328128, 8503951716838241] |