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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | 85 |
| 6 | 1707 |
| 7 | 37457 |
| 8 | 921896 |
| 9 | 25477371 |
| 10 | 786163135 |
| 11 | 26890701739 |
| 12 | 1012165431744 |
| 13 | 41638805754078 |
| 14 | 1860589088529164 |
| 15 | 89802422444553825 |
| 16 | 4658465562594667088 |
| 17 | 258566755450911870007 |
| 18 | 15294477441385413149679 |
| 19 | 960641026388207044487891 |
| 20 | 63861339527473864490450300 |
[0,0,0,4,85,1707,37457,921896,25477371,786163135, 26890701739,1012165431744,41638805754078, 1860589088529164,89802422444553825, 4658465562594667088,258566755450911870007, 15294477441385413149679,960641026388207044487891, 63861339527473864490450300] |