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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 12 |
| 4 | 216 |
| 5 | 3500 |
| 6 | 58494 |
| 7 | 1028167 |
| 8 | 18954072 |
| 9 | 363991752 |
| 10 | 7231521650 |
| 11 | 147777013109 |
| 12 | 3091874792274 |
| 13 | 65993049570175 |
| 14 | 1432803420182428 |
| 15 | 31570847522072400 |
| 16 | 704668366087255200 |
| 17 | 15907964778448807820 |
[0,0,12,216,3500,58494,1028167,18954072,363991752, 7231521650,147777013109,3091874792274, 65993049570175,1432803420182428,31570847522072400, 704668366087255200,15907964778448807820] |