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A323446 Number of binary strings w of length n that cannot be written in the form xyz, with x,z both nonempty and xz a square. 0
2, 2, 4, 6, 8, 12, 16, 26, 36, 70, 104, 220, 372, 758, 1408, 2874, 5472, 11056, 21696, 43546, 86060, 172514, 343068, 686888, 1369484, 2740080, 5471464, 10945900, 21872228, 43749868, 87460604, 174645564, 348957458 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A square is a nonempty block of the form XX.

LINKS

Table of n, a(n) for n=1..33.

EXAMPLE

For n = 6 the 12 solutions are {000001, 000011, 000111, 001011, 001111, 011111} and their complements.

CROSSREFS

Sequence in context: A080054 A108494 A078578 * A018129 A091915 A123862

Adjacent sequences:  A323443 A323444 A323445 * A323447 A323448 A323449

KEYWORD

nonn,more

AUTHOR

Jeffrey Shallit, Jan 15 2019

EXTENSIONS

a(21)-a(33) from Lars Blomberg, Jan 26 2019

STATUS

approved

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Last modified March 8 13:59 EST 2021. Contains 341949 sequences. (Running on oeis4.)