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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 36 |
| 3 | 195 |
| 4 | 1030 |
| 5 | 5375 |
| 6 | 27854 |
| 7 | 143695 |
| 8 | 738990 |
| 9 | 3791775 |
| 10 | 19421854 |
| 11 | 99344735 |
| 12 | 507597950 |
| 13 | 2591191375 |
| 14 | 13217410254 |
| 15 | 67376465775 |
| 16 | 343259079310 |
| 17 | 1747901098175 |
| 18 | 8896431461054 |
| 19 | 45262405898815 |
| 20 | 230195833919070 |
| 21 | 1170328696616175 |
[6,36,195,1030,5375,27854,143695,738990,3791775, 19421854,99344735,507597950,2591191375, 13217410254,67376465775,343259079310, 1747901098175,8896431461054,45262405898815, 230195833919070,1170328696616175] |