MathCastle
ChallengeMedium

Challenge · Medium problem

Let FnF_{n} denote the Fibonacci numbers with F1=F2=1F_{1}=F_{2}=1 and Fn+2=Fn+1+FnF_{n+2}=F_{n+1}+F_{n}. Evaluate ∑n=1∞Fn2n\displaystyle\sum_{n=1}^{\infty}\dfrac{F_{n}}{2^{n}}.

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