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| n | a(n) |
|---|---|
| 0 | -1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 18 |
| 7 | 34 |
| 8 | 68 |
| 9 | 125 |
| 10 | 250 |
| 11 | 461 |
| 12 | 922 |
| 13 | 1715 |
| 14 | 3430 |
| 15 | 6434 |
| 16 | 12868 |
| 17 | 24309 |
| 18 | 48618 |
| 19 | 92377 |
| 20 | 184754 |
| 21 | 352715 |
| 22 | 705430 |
| 23 | 1352077 |
| 24 | 2704154 |
| 25 | 5200299 |
| 26 | 10400598 |
| 27 | 20058299 |
| 28 | 40116598 |
| 29 | 77558759 |
| 30 | 155117518 |
| 31 | 300540194 |
| 32 | 601080388 |
| 33 | 1166803109 |
| 34 | 2333606218 |
| 35 | 4537567649 |
| 36 | 9075135298 |
| 37 | 17672631899 |
[-1,0,0,2,4,9,18,34,68,125,250,461,922,1715,3430, 6434,12868,24309,48618,92377,184754,352715,705430, 1352077,2704154,5200299,10400598,20058299, 40116598,77558759,155117518,300540194,601080388, 1166803109,2333606218,4537567649,9075135298, 17672631899] |