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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 26 |
| 5 | 2074 |
| 6 | 21660 |
| 7 | 2804068 |
| 8 | 33847970 |
| 9 | 5345496688 |
| 10 | 12201269878660 |
| 11 | 165029257057602 |
| 12 | 433037204976615540 |
| 13 | 85637003420093445994 |
| 14 | 1215603499085916654728 |
| 15 | 248871244937134915010626 |
| 16 | 753881874165723132009014662 |
| 17 | 2359161060012378685209851991166 |
[1,1,4,26,2074,21660,2804068,33847970,5345496688, 12201269878660,165029257057602,433037204976615540, 85637003420093445994,1215603499085916654728, 248871244937134915010626, 753881874165723132009014662, 2359161060012378685209851991166] |