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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 67 |
| 5 | 277 |
| 6 | 1025 |
| 7 | 3407 |
| 8 | 10265 |
| 9 | 28589 |
| 10 | 74945 |
| 11 | 187583 |
| 12 | 453167 |
| 13 | 1065257 |
| 14 | 2451317 |
| 15 | 5546819 |
| 16 | 12383627 |
| 17 | 27347117 |
| 18 | 59851121 |
| 19 | 130009223 |
| 20 | 280620167 |
| 21 | 602424305 |
| 22 | 1287187757 |
| 23 | 2739013259 |
| 24 | 5807246915 |
| 25 | 12272861813 |
| 26 | 25862365481 |
[1,4,16,67,277,1025,3407,10265,28589,74945,187583, 453167,1065257,2451317,5546819,12383627,27347117, 59851121,130009223,280620167,602424305,1287187757, 2739013259,5807246915,12272861813,25862365481] |