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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 10 |
| 4 | 22 |
| 5 | 50 |
| 6 | 119 |
| 7 | 276 |
| 8 | 637 |
| 9 | 1473 |
| 10 | 3355 |
| 11 | 7682 |
| 12 | 17497 |
| 13 | 39777 |
| 14 | 90406 |
| 15 | 205111 |
| 16 | 465359 |
| 17 | 1054871 |
| 18 | 2390302 |
| 19 | 5415591 |
| 20 | 12265608 |
| 21 | 27777095 |
| 22 | 62895884 |
| 23 | 142401878 |
| 24 | 322392952 |
| 25 | 729835421 |
| 26 | 1652150714 |
| 27 | 3739914222 |
| 28 | 8465684665 |
| 29 | 19162662378 |
| 30 | 43375394510 |
[2,4,10,22,50,119,276,637,1473,3355,7682,17497, 39777,90406,205111,465359,1054871,2390302,5415591, 12265608,27777095,62895884,142401878,322392952, 729835421,1652150714,3739914222,8465684665, 19162662378,43375394510] |