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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 25 |
| 4 | 146 |
| 5 | 1074 |
| 6 | 9247 |
| 7 | 89618 |
| 8 | 956106 |
| 9 | 11066959 |
| 10 | 137531624 |
| 11 | 1820347008 |
| 12 | 25499542444 |
| 13 | 376098118280 |
| 14 | 5815744322556 |
| 15 | 93946244699173 |
| 16 | 1580463050838884 |
| 17 | 27616009578136506 |
| 18 | 500029604169802336 |
| 19 | 9362566904514285044 |
[1,2,6,25,146,1074,9247,89618,956106,11066959, 137531624,1820347008,25499542444,376098118280, 5815744322556,93946244699173,1580463050838884, 27616009578136506,500029604169802336, 9362566904514285044] |