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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 87 |
| 4 | 585 |
| 5 | 4383 |
| 6 | 35919 |
| 7 | 318195 |
| 8 | 3015441 |
| 9 | 30354075 |
| 10 | 322626159 |
| 11 | 3603292047 |
| 12 | 42120047385 |
| 13 | 513557128503 |
| 14 | 6512375759535 |
| 15 | 85673471945067 |
| 16 | 1166675225150241 |
| 17 | 16413589529042355 |
| 18 | 238151194659626319 |
| 19 | 3558129109803374535 |
[1,3,15,87,585,4383,35919,318195,3015441,30354075, 322626159,3603292047,42120047385,513557128503, 6512375759535,85673471945067,1166675225150241, 16413589529042355,238151194659626319, 3558129109803374535] |