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A094425
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Numbers n such that F_n(x) and F_n(1-x) have a common factor mod 2, with F_n(x) = U(n-1,x/2) the monic Chebyshev polynomials of second kind; this lists only the primitive elements of the set.
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2
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5, 6, 17, 31, 33, 63, 127, 129, 171, 257, 511, 683, 2047, 2731, 2979, 3277, 3641, 8191, 28197, 43691, 48771, 52429, 61681, 65537, 85489, 131071
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OFFSET
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1,1
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COMMENTS
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Klaus Sutner, Jun 26 2006, remarks that it can be shown that this sequence is infinite.
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REFERENCES
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Dieter Gebhardt, "Cross pattern puzzles revisited," Cubism For Fun 69 (March 2006), 23-25.
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LINKS
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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Gebhardt and Sutner references from Don Knuth, May 11 2006
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STATUS
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approved
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