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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 17 |
| 3 | 42 |
| 4 | 109 |
| 5 | 288 |
| 6 | 755 |
| 7 | 1974 |
| 8 | 5167 |
| 9 | 13530 |
| 10 | 35423 |
| 11 | 92736 |
| 12 | 242785 |
| 13 | 635622 |
| 14 | 1664081 |
| 15 | 4356618 |
| 16 | 11405773 |
| 17 | 29860704 |
| 18 | 78176339 |
| 19 | 204668310 |
| 20 | 535828591 |
| 21 | 1402817466 |
| 22 | 3672623807 |
| 23 | 9615053952 |
| 24 | 25172538049 |
| 25 | 65902560198 |
| 26 | 172535142545 |
[1,6,17,42,109,288,755,1974,5167,13530,35423, 92736,242785,635622,1664081,4356618,11405773, 29860704,78176339,204668310,535828591,1402817466, 3672623807,9615053952,25172538049,65902560198, 172535142545] |