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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 9 |
| 2 | 38 |
| 3 | 161 |
| 4 | 680 |
| 5 | 2872 |
| 6 | 12128 |
| 7 | 51214 |
| 8 | 216264 |
| 9 | 913228 |
| 10 | 3856328 |
| 11 | 16284284 |
| 12 | 68764352 |
| 13 | 290374208 |
| 14 | 1226175744 |
| 15 | 5177825416 |
| 16 | 21864627616 |
| 17 | 92328709904 |
| 18 | 389880441696 |
| 19 | 1646365025296 |
| 20 | 6952176889728 |
| 21 | 29357258422912 |
| 22 | 123968166486528 |
| 23 | 523485745182432 |
| 24 | 2210545926231680 |
[2,9,38,161,680,2872,12128,51214,216264,913228, 3856328,16284284,68764352,290374208,1226175744, 5177825416,21864627616,92328709904,389880441696, 1646365025296,6952176889728,29357258422912, 123968166486528,523485745182432,2210545926231680] |