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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 63 |
| 3 | 399 |
| 4 | 2403 |
| 5 | 14067 |
| 6 | 80949 |
| 7 | 460845 |
| 8 | 2605590 |
| 9 | 14666470 |
| 10 | 82320714 |
| 11 | 461238282 |
| 12 | 2581644378 |
| 13 | 14442658074 |
| 14 | 80785970838 |
| 15 | 451934259654 |
| 16 | 2528977211775 |
| 17 | 14157983986839 |
| 18 | 79302044283297 |
| 19 | 444448115168049 |
| 20 | 2492468172937125 |
[1,9,63,399,2403,14067,80949,460845,2605590, 14666470,82320714,461238282,2581644378, 14442658074,80785970838,451934259654, 2528977211775,14157983986839,79302044283297, 444448115168049,2492468172937125] |