MathDB
Fibonacci hops in the Euclidean plane

Source: ICMC 2023 Round 1 P3

November 28, 2022
ICMCcombinatoricsFibonaccicollege contests

Problem Statement

Bugs Bunny plays a game in the Euclidean plane. At the nn-th minute (n1)(n \geq 1), Bugs Bunny hops a distance of FnF_n in the North, South, East, or West direction, where FnF_n is the nn-th Fibonacci number (defined by F1=F2=1F_1 = F_2 =1 and Fn=Fn1+Fn2F_n = F_{n-1} + F_{n-2} for n3n \geq 3). If the first two hops were perpendicular, prove that Bugs Bunny can never return to where he started.
Proposed by Dylan Toh