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

Contributed by Shuta Iwai

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.

Primarily human-written textHuman understanding: all parts

Nov 02, 2026PDF ↗View work →

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

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