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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 28 |
| 5 | 99 |
| 6 | 356 |
| 7 | 1328 |
| 8 | 5097 |
| 9 | 19960 |
| 10 | 79422 |
| 11 | 320690 |
| 12 | 1310179 |
| 13 | 5406116 |
| 14 | 22506438 |
| 15 | 94405329 |
| 16 | 398676354 |
| 17 | 1693626888 |
| 18 | 7233208542 |
| 19 | 31039546830 |
| 20 | 133775260725 |
| 21 | 578814117990 |
| 22 | 2513364385989 |
| 23 | 10949535309451 |
| 24 | 47845898589287 |
| 25 | 209653653580245 |
| 26 | 921041289040822 |
| 27 | 4055976376939685 |
| 28 | 17901115589094040 |
[1,1,3,9,28,99,356,1328,5097,19960,79422,320690, 1310179,5406116,22506438,94405329,398676354, 1693626888,7233208542,31039546830,133775260725, 578814117990,2513364385989,10949535309451, 47845898589287,209653653580245,921041289040822, 4055976376939685,17901115589094040] |