

A094425


Numbers n such that F_n(x) and F_n(1x) have a common factor mod 2, with F_n(x) = U(n1,x/2) the monic Chebyshev polynomials of second kind; this lists only the primitive elements of the set.


2



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

1,1


COMMENTS

Klaus Sutner, Jun 26 2006, remarks that it can be shown that this sequence is infinite.


REFERENCES

Dieter Gebhardt, "Cross pattern puzzles revisited," Cubism For Fun 69 (March 2006), 2325.


LINKS

Table of n, a(n) for n=1..26.
K. Sutner, Linear cellular automata and the GardenofEden, Math. Intelligencer, 11 (No. 2, 1989), 4953.
K. Sutner, The computational complexity of cellular automata, in Lect. Notes Computer Sci., 380 (1989), 451459.
K. Sutner, sigmaAutomata and Chebyshevpolynomials, Theoretical Comp. Sci., 230 (2000), 4973.
M. Hunziker, A. Machiavelo and J. Park, Chebyshev polynomials over finite fields and reversibility of sigmaautomata on square grids, Theoretical Comp. Sci., 320 (2004), 465483.
Eric Weisstein's World of Mathematics, LightsOut Puzzle


CROSSREFS

Cf. A093614 (all elements), A076436.
Sequence in context: A041054 A297980 A120034 * A078981 A041555 A041747
Adjacent sequences: A094422 A094423 A094424 * A094426 A094427 A094428


KEYWORD

nonn,hard,more


AUTHOR

Ralf Stephan, May 22 2004


EXTENSIONS

Gebhardt and Sutner references from Don Knuth, May 11 2006


STATUS

approved



