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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 134 |
| 6 | 622 |
| 7 | 3106 |
| 8 | 16720 |
| 9 | 95140 |
| 10 | 572638 |
| 11 | 3621722 |
| 12 | 24046746 |
| 13 | 166799374 |
| 14 | 1205714772 |
| 15 | 9043761626 |
| 16 | 70185282194 |
| 17 | 561924753756 |
| 18 | 4632640872604 |
| 19 | 39262210040594 |
| 20 | 341678806496748 |
| 21 | 3050007040331626 |
| 22 | 27902744129363050 |
| 23 | 261376205797957108 |
| 24 | 2504865765980461010 |
[1,1,3,9,33,134,622,3106,16720,95140,572638, 3621722,24046746,166799374,1205714772,9043761626, 70185282194,561924753756,4632640872604, 39262210040594,341678806496748,3050007040331626, 27902744129363050,261376205797957108, 2504865765980461010] |