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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 0 |
| 5 | 20 |
| 6 | 105 |
| 7 | 504 |
| 8 | 4480 |
| 9 | 43560 |
| 10 | 424305 |
| 11 | 4613840 |
| 12 | 55668096 |
| 13 | 724667580 |
| 14 | 10136511385 |
| 15 | 152029000200 |
| 16 | 2432747715840 |
| 17 | 41357024915024 |
| 18 | 744416488494945 |
| 19 | 14143911946532640 |
| 20 | 282878618744592640 |
| 21 | 5940450667217358180 |
| 22 | 130689899053015493961 |
| 23 | 3005867708207562586520 |
[0,0,1,0,0,20,105,504,4480,43560,424305,4613840, 55668096,724667580,10136511385,152029000200, 2432747715840,41357024915024,744416488494945, 14143911946532640,282878618744592640, 5940450667217358180,130689899053015493961, 3005867708207562586520] |