

A216214


Number of (strongly) superprimitive binary sequences of length n.


1



1, 2, 2, 4, 6, 8, 16, 24, 46, 84, 160, 300, 588, 1136, 2236, 4388, 8690
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OFFSET

0,2


COMMENTS

A string x of length n is (weakly) quasiperiodic if there is a string w of length < n for which copies can be placed (possibly overlapping; possibly hanging off the left and right ends of x) that completely cover x. For example, x = 001101 is weakly quasiperiodic with quasiperiod w = 0110; three copies of w suffice to cover x. A string is (strongly) superprimitive if it is not weakly quasiperiodic.


LINKS



EXAMPLE

a(6) = 16 because the 8 strings
000001,
000011,
000101,
000111,
001011,
001111,
010111,
011111
and their complements are strongly superprimitive.


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



