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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 256 |
| 5 | 4864 |
| 6 | 111616 |
| 7 | 2983936 |
| 8 | 89743360 |
| 9 | 2970861568 |
| 10 | 106768629760 |
| 11 | 4125849419776 |
| 12 | 170207219286016 |
| 13 | 7454572671926272 |
| 14 | 345078981839552512 |
| 15 | 16822127738969128960 |
| 16 | 860944587541763325952 |
| 17 | 46137178395559050870784 |
| 18 | 2582843669636660403896320 |
| 19 | 150735442996358913332346880 |
[1,4,16,256,4864,111616,2983936,89743360, 2970861568,106768629760,4125849419776, 170207219286016,7454572671926272, 345078981839552512,16822127738969128960, 860944587541763325952,46137178395559050870784, 2582843669636660403896320, 150735442996358913332346880] |