A309011 - OEIS

A309011

Lexicographically earliest sequence of nonnegative integers such that for any n > 0, the palindromic word (a(n), a(n-1), ..., a(1), a(0), a(1), ..., a(n-1), a(n)) is squarefree.

0, 1, 2, 0, 1, 0, 2, 0, 1, 2, 0, 2, 1, 0, 1, 2, 0, 1, 0, 2, 0, 1, 3, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 2, 0, 2, 1, 0, 1, 2, 0, 1, 0, 2, 0, 1, 2, 0, 2, 1, 0, 1, 3, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 2, 0, 2, 1, 0, 1, 2, 0, 1, 0, 2, 0, 1, 2, 0, 2

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OFFSET

0,3

COMMENTS

A word is squarefree if it has no subsequence of the form XX.

This sequence has similarities with A007814, the lexicographically earliest squarefree sequence of nonnegative integers.

Is this sequence unbounded?

LINKS

Table of n, a(n) for n=0..86.

Rémy Sigrist, C program for A309011

EXAMPLE

For n = 0: