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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 442 |
| 3 | 2464 |
| 4 | 13720 |
| 5 | 76404 |
| 6 | 424600 |
| 7 | 2361716 |
| 8 | 13136192 |
| 9 | 73071732 |
| 10 | 406402784 |
| 11 | 2260476660 |
| 12 | 12572745216 |
| 13 | 69931253876 |
| 14 | 388958563328 |
| 15 | 2163420804596 |
| 16 | 12033035388224 |
| 17 | 66928590189940 |
| 18 | 372260237706816 |
| 19 | 2070535450010484 |
[81,442,2464,13720,76404,424600,2361716,13136192, 73071732,406402784,2260476660,12572745216, 69931253876,388958563328,2163420804596, 12033035388224,66928590189940,372260237706816, 2070535450010484] |