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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 15 |
| 3 | 51 |
| 4 | 754 |
| 5 | 803 |
| 6 | 2160 |
| 7 | 3048 |
| 8 | 8315 |
| 9 | 18549 |
| 10 | 27094 |
| 11 | 89929 |
| 12 | 251712 |
| 13 | 505768 |
| 14 | 936240 |
| 15 | 1617182 |
| 16 | 2182656 |
| 17 | 2582372 |
| 18 | 5116884 |
| 19 | 27067121 |
| 20 | 77131559 |
[6,15,51,754,803,2160,3048,8315,18549,27094,89929, 251712,505768,936240,1617182,2182656,2582372, 5116884,27067121,77131559] |