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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 16 |
| 5 | 230 |
| 6 | 3480 |
| 7 | 57379 |
| 8 | 1038016 |
| 9 | 20570444 |
| 10 | 444647600 |
| 11 | 10431670821 |
| 12 | 264300628944 |
| 13 | 7198061846898 |
| 14 | 209814739262856 |
| 15 | 6520139954328519 |
| 16 | 215245451727154944 |
| 17 | 7524314127912551832 |
| 18 | 277705505168550027360 |
| 19 | 10792700030471840300745 |
| 20 | 440604294676004639627280 |
[1,16,230,3480,57379,1038016,20570444,444647600, 10431670821,264300628944,7198061846898, 209814739262856,6520139954328519, 215245451727154944,7524314127912551832, 277705505168550027360,10792700030471840300745, 440604294676004639627280] |