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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 49 |
| 5 | 321 |
| 6 | 2131 |
| 7 | 19783 |
| 8 | 195777 |
| 9 | 2101249 |
| 10 | 25721731 |
| 11 | 340358151 |
| 12 | 4902173233 |
| 13 | 75688032577 |
| 14 | 1253701725459 |
| 15 | 22347046050631 |
| 16 | 418439924732161 |
| 17 | 8318748086461953 |
| 18 | 175769214730290307 |
| 19 | 3871849719998940679 |
| 20 | 89734800330818444721 |
| 21 | 2187944831367633226561 |
[1,1,3,7,49,321,2131,19783,195777,2101249, 25721731,340358151,4902173233,75688032577, 1253701725459,22347046050631,418439924732161, 8318748086461953,175769214730290307, 3871849719998940679,89734800330818444721, 2187944831367633226561] |