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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 17 |
| 4 | 75 |
| 5 | 285 |
| 6 | 1317 |
| 7 | 5567 |
| 8 | 25985 |
| 9 | 114405 |
| 10 | 542049 |
| 11 | 2456039 |
| 12 | 11720847 |
| 13 | 54060867 |
| 14 | 259872549 |
| 15 | 1214918367 |
| 16 | 5866220625 |
| 17 | 27689646713 |
| 18 | 134259837463 |
| 19 | 638654468767 |
| 20 | 3105757823623 |
| 21 | 14861570751109 |
| 22 | 72466412558809 |
| 23 | 348482332573211 |
| 24 | 1702720911060097 |
| 25 | 8220802950971551 |
| 26 | 40243093261609041 |
| 27 | 194955190455663275 |
[1,1,5,17,75,285,1317,5567,25985,114405,542049, 2456039,11720847,54060867,259872549,1214918367, 5866220625,27689646713,134259837463,638654468767, 3105757823623,14861570751109,72466412558809, 348482332573211,1702720911060097,8220802950971551, 40243093261609041,194955190455663275] |