Delphi.science

On a Family of Counterexamples to Richard Guy's Mex Sequence Problem

Shuta Iwai

Hexagonhexagon/2610.00735Nov 2, 2026math.NTscore 0

We give a family of counterexamples to Richard Guy's problem E27 with initial terms of length five adding onto the recent example of length eight. Additionally, we prove that for length one, one always has a ultimately periodic sequence. Lastly we pose a problem regarding the notion of a zth mex sequence.

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