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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 52 |
| 4 | 1504 |
| 5 | 145984 |
| 6 | 48461696 |
| 7 | 56141454464 |
| 8 | 229148544420864 |
| 9 | 3333310786076963968 |
| 10 | 174695272746603272722432 |
| 11 | 33301710992539090379269318144 |
| 12 | 23278728241293494481773139193036800 |
| 13 | 60084295633556503802059558812644803074048 |
| 14 | 576025077880237078776946485247979728479746359296 |
[0,1,4,52,1504,145984,48461696,56141454464, 229148544420864,3333310786076963968, 174695272746603272722432, 33301710992539090379269318144, 23278728241293494481773139193036800, 60084295633556503802059558812644803074048, 576025077880237078776946485247979728479746359296] |