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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 31 |
| 4 | 736 |
| 5 | 15601 |
| 6 | 310591 |
| 7 | 5941456 |
| 8 | 110557921 |
| 9 | 2015926111 |
| 10 | 36192227776 |
| 11 | 641841785041 |
| 12 | 11270021820031 |
| 13 | 196270140120496 |
| 14 | 3394577405818561 |
| 15 | 58366312816456351 |
| 16 | 998470947372051616 |
| 17 | 17005480407434466481 |
| 18 | 288506014395807323071 |
| 19 | 4877820327227979669136 |
| 20 | 82217261607226450096801 |
[0,0,1,31,736,15601,310591,5941456,110557921, 2015926111,36192227776,641841785041, 11270021820031,196270140120496,3394577405818561, 58366312816456351,998470947372051616, 17005480407434466481,288506014395807323071, 4877820327227979669136,82217261607226450096801] |