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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 15 |
| 4 | 224 |
| 5 | 4545 |
| 6 | 126753 |
| 7 | 4626076 |
| 8 | 213703095 |
| 9 | 12167727543 |
| 10 | 835893746300 |
| 11 | 68091766034061 |
| 12 | 6483302813035857 |
| 13 | 712860388963255000 |
| 14 | 89585739948801890619 |
| 15 | 12753524767335858733935 |
| 16 | 2040804997678590563632568 |
| 17 | 364567987004433619078313961 |
[1,0,3,15,224,4545,126753,4626076,213703095, 12167727543,835893746300,68091766034061, 6483302813035857,712860388963255000, 89585739948801890619,12753524767335858733935, 2040804997678590563632568, 364567987004433619078313961] |