Harvard MIT Math Tournament (HMMT), Problem of The Week (PoTW), Method 2

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In/E k->1 Fⁿ/4n+1->½+½->4ⁿ+1->¼, Fⁿ->¼+Fⁿ¼

UzziWallendorf
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Very nice! It is like solving witg generating function, just without the generating function and with great explanation.well done!😀💯

yoav
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Method 3 can be take A(x)= sum Fn x^n n varies from 0 to inf...as generating function for the sequence...use Fn=Fn-1+Fn-2 to get A(x)=1/(1-x-x^2) and put x=1/4

debrajbanerjee