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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 9 |
| 3 | 42 |
| 4 | 205 |
| 5 | 997 |
| 6 | 4850 |
| 7 | 23593 |
| 8 | 114769 |
| 9 | 558298 |
| 10 | 2715861 |
| 11 | 13211405 |
| 12 | 64267362 |
| 13 | 312630929 |
| 14 | 1520804569 |
| 15 | 7398009354 |
| 16 | 35987886621 |
| 17 | 175064388469 |
| 18 | 851607109714 |
| 19 | 4142673879353 |
| 20 | 20152188344737 |
| 21 | 98031056006074 |
| 22 | 476875651282597 |
[2,9,42,205,997,4850,23593,114769,558298,2715861, 13211405,64267362,312630929,1520804569,7398009354, 35987886621,175064388469,851607109714, 4142673879353,20152188344737,98031056006074, 476875651282597] |