

A305594


Number of cyclic binary sequences of length n containing no abelian 4th powers.


0



2, 3, 4, 4, 4, 8, 10, 14, 12, 20, 34, 33, 52, 61, 76, 96, 126, 200, 258, 442, 568
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OFFSET

1,1


COMMENTS

Two lengthn sequences are considered to be the same in the cyclic sense if one is a cyclic shift of the other.
An abelian 4th power is a word of the form x x' x'' x''', where x', x'', x''' are all permutations of x.


LINKS

Table of n, a(n) for n=1..21.


EXAMPLE

a(7) = 10, and the cyclic words are {0001001, 0001011, 0001101, 0010011, 0010101, 0010111, 0011011, 0011101, 0101011, 0110111}.


CROSSREFS

Sequence in context: A076410 A309941 A211509 * A320778 A058277 A065852
Adjacent sequences: A305591 A305592 A305593 * A305595 A305596 A305597


KEYWORD

nonn,more


AUTHOR

Jeffrey Shallit, Jun 05 2018


STATUS

approved



