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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 27 |
| 4 | 109 |
| 5 | 460 |
| 6 | 2003 |
| 7 | 8904 |
| 8 | 40189 |
| 9 | 183714 |
| 10 | 848507 |
| 11 | 3951059 |
| 12 | 18522979 |
| 13 | 87344376 |
| 14 | 413914957 |
| 15 | 1969793273 |
| 16 | 9408674499 |
| 17 | 45086299096 |
| 18 | 216670214407 |
| 19 | 1043878328587 |
| 20 | 5040588953405 |
| 21 | 24388975543606 |
| 22 | 118222008081305 |
| 23 | 574011027579190 |
| 24 | 2791223195141009 |
| 25 | 13591387992099396 |
| 26 | 66263906445704581 |
[1,2,7,27,109,460,2003,8904,40189,183714,848507, 3951059,18522979,87344376,413914957,1969793273, 9408674499,45086299096,216670214407,1043878328587, 5040588953405,24388975543606,118222008081305, 574011027579190,2791223195141009, 13591387992099396,66263906445704581] |