The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 9 |
| 3 | 12 |
| 4 | 18 |
| 5 | 27 |
| 6 | 39 |
| 7 | 84 |
| 8 | 180 |
| 9 | 405 |
| 10 | 1146 |
| 11 | 3771 |
| 12 | 16968 |
| 13 | 124920 |
| 14 | 1300698 |
| 15 | 21030543 |
| 16 | 789446775 |
| 17 | 66335193975 |
| 18 | 12789617792358 |
| 19 | 8055533977534854 |
| 20 | 25842724292300950836 |
| 21 | 420717890555423371185381 |
[6,9,12,18,27,39,84,180,405,1146,3771,16968, 124920,1300698,21030543,789446775,66335193975, 12789617792358,8055533977534854, 25842724292300950836,420717890555423371185381] |