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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 51 |
| 3 | 1695 |
| 4 | 85524 |
| 5 | 5826402 |
| 6 | 501281256 |
| 7 | 52178851302 |
| 8 | 6378309961152 |
| 9 | 895845418408992 |
| 10 | 142179729906910680 |
| 11 | 25166131508370202776 |
| 12 | 4915451890368514588032 |
| 13 | 1050225776987234559170976 |
| 14 | 243664809398578134394019712 |
| 15 | 61008419406811276254021582384 |
[1,3,51,1695,85524,5826402,501281256,52178851302, 6378309961152,895845418408992,142179729906910680, 25166131508370202776,4915451890368514588032, 1050225776987234559170976, 243664809398578134394019712, 61008419406811276254021582384] |