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 A066499 Numbers k such that phi(k) == 2 (mod 4). 8
 3, 4, 6, 7, 9, 11, 14, 18, 19, 22, 23, 27, 31, 38, 43, 46, 47, 49, 54, 59, 62, 67, 71, 79, 81, 83, 86, 94, 98, 103, 107, 118, 121, 127, 131, 134, 139, 142, 151, 158, 162, 163, 166, 167, 179, 191, 199, 206, 211, 214, 223, 227, 239, 242, 243, 251, 254, 262, 263, 271 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Related to the equation x^4 = 1 (mod y): sequence gives values of n such x^4 = 1 (mod n) has no solution 1 < x < n-1. k is of the form p^m or 2*p^m where p is A002145 (with the exception of a(2)=4). All prime numbers here belong also to A002145, prime numbers of the form 4n+3. - Enrique Pérez Herrero, Sep 07 2011 REFERENCES W. J. LeVeque, Fundamentals of Number Theory, pp. 57 Problem 15, Dover NY 1996. LINKS Harry J. Smith, Table of n, a(n) for n = 1..1000 MATHEMATICA Select[Range[300], Mod[EulerPhi[#], 4]==2&] (* Harvey P. Dale, Feb 18 2018 *) PROG (PARI) { n=0; for (m=1, 10^10, if (eulerphi(m)%4 == 2, write("b066499.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 18 2010 CROSSREFS Cf. A066498, A066500, A066501, A066502, A000010. Essentially the same as A097987. Sequence in context: A006855 A301766 A229173 * A201471 A338387 A360799 Adjacent sequences: A066496 A066497 A066498 * A066500 A066501 A066502 KEYWORD nonn AUTHOR Benoit Cloitre, Jan 04 2002 EXTENSIONS Simpler definition from Lekraj Beedassy, Jul 21 2003 Corrected and extended by Ray Chandler, Nov 06 2003 STATUS approved

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Last modified December 7 18:28 EST 2023. Contains 367660 sequences. (Running on oeis4.)