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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 26 |
| 5 | 296 |
| 6 | 6064 |
| 7 | 230896 |
| 8 | 16886864 |
| 9 | 2423185664 |
| 10 | 687883494016 |
| 11 | 387139470010624 |
| 12 | 432380088071584256 |
| 13 | 959252253993204724736 |
| 14 | 4231267540316814507357184 |
| 15 | 37138269572860613284747227136 |
| 16 | 649037449132671895468073434916864 |
| 17 | 22596879313063804832510513481261154304 |
[0,0,1,4,26,296,6064,230896,16886864,2423185664, 687883494016,387139470010624,432380088071584256, 959252253993204724736,4231267540316814507357184, 37138269572860613284747227136, 649037449132671895468073434916864, 22596879313063804832510513481261154304] |