

A004169


Values of n for which a regular polygon with n sides cannot be constructed with ruler and compass.


4



7, 9, 11, 13, 14, 18, 19, 21, 22, 23, 25, 26, 27, 28, 29, 31, 33, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 86, 87, 88, 89, 90, 91
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OFFSET

1,1


COMMENTS

Numbers m for which phi(a(m)) is not a power of 2, phi = A000010, Euler's totient function.  Reinhard Zumkeller, Jul 31 2012


REFERENCES

A. H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1964, p. 183.
C. F. Gauss, Disquisitiones Arithmeticae, 1801. English translation: Yale University Press, New Haven, CT, 1966, p. 460.
B. L. van der Waerden, Modern Algebra. Unger, NY, 2nd ed., Vols. 12, 1953, Vol. 1, p. 187.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000
C. F. Gauss, Disquisitiones Arithmeticae, Lipsiae, 1801. Reprinted in C. F. Gauss, Werke, 1863.


MATHEMATICA

Select[ Range[75], !IntegerQ[ Log[2, EulerPhi[#] ] ]& ] (* JeanFrançois Alcover, Nov 24 2011, after A003401 *)


PROG

(Haskell)
a004169 n = a004169_list !! (n1)
a004169_list = map (+ 1) $ elemIndices 0 $ map a209229 a000010_list
 Reinhard Zumkeller, Jul 31 2012


CROSSREFS

Cf. A003401 (complement).
Cf. A000010, A209229.
Sequence in context: A108815 A161992 A167377 * A066669 A059808 A020742
Adjacent sequences: A004166 A004167 A004168 * A004170 A004171 A004172


KEYWORD

nonn,nice


AUTHOR

N. J. A. Sloane, Branislav Kisacanin (bkisacan(AT)eecs.uic.edu)


STATUS

approved



