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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 72 |
| 4 | 463 |
| 5 | 4030 |
| 6 | 28908 |
| 7 | 231393 |
| 8 | 1733366 |
| 9 | 13499224 |
| 10 | 102723495 |
| 11 | 792454734 |
| 12 | 6063888364 |
| 13 | 46624820793 |
| 14 | 357473932822 |
| 15 | 2745399810920 |
| 16 | 21063557869407 |
| 17 | 161702118409342 |
| 18 | 1240928795315404 |
| 19 | 9525079068251761 |
| 20 | 73103241532364950 |
[1,6,72,463,4030,28908,231393,1733366,13499224, 102723495,792454734,6063888364,46624820793, 357473932822,2745399810920,21063557869407, 161702118409342,1240928795315404,9525079068251761, 73103241532364950] |