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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 15 |
| 3 | 73 |
| 4 | 355 |
| 5 | 1727 |
| 6 | 8401 |
| 7 | 40867 |
| 8 | 198799 |
| 9 | 967065 |
| 10 | 4704323 |
| 11 | 22884351 |
| 12 | 111321761 |
| 13 | 541528771 |
| 14 | 2634286479 |
| 15 | 12814582761 |
| 16 | 62337005731 |
| 17 | 303240640447 |
| 18 | 1475125167473 |
| 19 | 7175800237411 |
| 20 | 34906942259983 |
| 21 | 169806095157049 |
| 22 | 826027949905539 |
[3,15,73,355,1727,8401,40867,198799,967065, 4704323,22884351,111321761,541528771,2634286479, 12814582761,62337005731,303240640447, 1475125167473,7175800237411,34906942259983, 169806095157049,826027949905539] |