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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 29 |
| 4 | 288 |
| 5 | 3649 |
| 6 | 56160 |
| 7 | 1017029 |
| 8 | 21181440 |
| 9 | 498682881 |
| 10 | 13095232000 |
| 11 | 379443829709 |
| 12 | 12025239367680 |
| 13 | 413761766695809 |
| 14 | 15360425115176960 |
| 15 | 611958601019294325 |
| 16 | 26042588632355176448 |
| 17 | 1179009749826940037889 |
| 18 | 56579126414696034729984 |
| 19 | 2868848293506101088635389 |
[0,1,4,29,288,3649,56160,1017029,21181440, 498682881,13095232000,379443829709,12025239367680, 413761766695809,15360425115176960, 611958601019294325,26042588632355176448, 1179009749826940037889,56579126414696034729984, 2868848293506101088635389] |