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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 64 |
| 4 | 504 |
| 5 | 4368 |
| 6 | 40208 |
| 7 | 385728 |
| 8 | 3813888 |
| 9 | 38590208 |
| 10 | 397648384 |
| 11 | 4158436864 |
| 12 | 44020882944 |
| 13 | 470804670464 |
| 14 | 5079479547904 |
| 15 | 55217003536384 |
| 16 | 604200374845440 |
| 17 | 6649658071007232 |
| 18 | 73560096496779264 |
| 19 | 817467602640830464 |
| 20 | 9121818467786162176 |
[1,3,10,64,504,4368,40208,385728,3813888,38590208, 397648384,4158436864,44020882944,470804670464, 5079479547904,55217003536384,604200374845440, 6649658071007232,73560096496779264, 817467602640830464,9121818467786162176] |