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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 8 |
| 3 | 25 |
| 4 | 57 |
| 5 | 156 |
| 6 | 384 |
| 7 | 1009 |
| 8 | 2545 |
| 9 | 6580 |
| 10 | 16760 |
| 11 | 43081 |
| 12 | 110121 |
| 13 | 282444 |
| 14 | 722928 |
| 15 | 1852705 |
| 16 | 4744417 |
| 17 | 12155236 |
| 18 | 31132904 |
| 19 | 79753849 |
| 20 | 204285465 |
| 21 | 523300860 |
| 22 | 1340442720 |
| 23 | 3433646161 |
| 24 | 8795417041 |
| 25 | 22530001684 |
| 26 | 57711669848 |
| 27 | 147831676585 |
[4,8,25,57,156,384,1009,2545,6580,16760,43081, 110121,282444,722928,1852705,4744417,12155236, 31132904,79753849,204285465,523300860,1340442720, 3433646161,8795417041,22530001684,57711669848, 147831676585] |