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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 69 |
| 4 | 531 |
| 5 | 4902 |
| 6 | 50829 |
| 7 | 572205 |
| 8 | 6862689 |
| 9 | 86688894 |
| 10 | 1144856748 |
| 11 | 15729634734 |
| 12 | 224087784921 |
| 13 | 3302687639634 |
| 14 | 50281130534937 |
| 15 | 789933587289762 |
| 16 | 12797723149002135 |
| 17 | 213714114688378335 |
| 18 | 3677422015083776007 |
| 19 | 65182431142298139342 |
| 20 | 1189739115108589181733 |
| 21 | 22353074429721448236369 |
[1,3,12,69,531,4902,50829,572205,6862689,86688894, 1144856748,15729634734,224087784921,3302687639634, 50281130534937,789933587289762,12797723149002135, 213714114688378335,3677422015083776007, 65182431142298139342,1189739115108589181733, 22353074429721448236369] |