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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 92 |
| 5 | 450 |
| 6 | 14454 |
| 7 | 141540 |
| 8 | 4980128 |
| 9 | 78711696 |
| 10 | 3048567480 |
| 11 | 68677353360 |
| 12 | 2930551701384 |
| 13 | 86832573553440 |
| 14 | 4079649847428960 |
| 15 | 150444517302424800 |
| 16 | 7768028697749806080 |
| 17 | 342721736137376184960 |
| 18 | 19392702029822685015360 |
| 19 | 994397473912386435004800 |
[1,0,2,3,92,450,14454,141540,4980128,78711696, 3048567480,68677353360,2930551701384, 86832573553440,4079649847428960, 150444517302424800,7768028697749806080, 342721736137376184960,19392702029822685015360, 994397473912386435004800] |