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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 9 |
| 4 | 21 |
| 5 | 51 |
| 6 | 127 |
| 7 | 323 |
| 8 | 835 |
| 9 | 15511 |
| 10 | 41835 |
| 11 | 853467 |
| 12 | 2356779 |
| 13 | 50852019 |
| 14 | 142547559 |
| 15 | 400763223 |
| 16 | 1129760415 |
| 17 | 3192727797 |
| 18 | 9043402501 |
| 19 | 208023278209 |
| 20 | 593742784829 |
| 21 | 1697385471211 |
| 22 | 4859761676391 |
| 23 | 13933569346707 |
| 24 | 40002464776083 |
| 25 | 953467954114363 |
| 26 | 2750016719520991 |
| 27 | 7939655757745265 |
[1,1,9,21,51,127,323,835,15511,41835,853467, 2356779,50852019,142547559,400763223,1129760415, 3192727797,9043402501,208023278209,593742784829, 1697385471211,4859761676391,13933569346707, 40002464776083,953467954114363,2750016719520991, 7939655757745265] |