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| n | a(n) |
|---|---|
| 1 | 64 |
| 2 | 3281 |
| 3 | 4355 |
| 4 | 18189 |
| 5 | 60540 |
| 6 | 198619 |
| 7 | 639142 |
| 8 | 2039214 |
| 9 | 6489813 |
| 10 | 20683647 |
| 11 | 65987467 |
| 12 | 210970521 |
| 13 | 675532316 |
| 14 | 2165041339 |
| 15 | 6942289440 |
| 16 | 22270716585 |
| 17 | 71468916039 |
| 18 | 229423662632 |
| 19 | 736691206279 |
| 20 | 2366141286606 |
| 21 | 7601378517849 |
[64,3281,4355,18189,60540,198619,639142,2039214, 6489813,20683647,65987467,210970521,675532316, 2165041339,6942289440,22270716585,71468916039, 229423662632,736691206279,2366141286606, 7601378517849] |