A066499 Numbers k such that phi(k) == 2 (mod 4).

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

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) isok(k) = { eulerphi(k)%4 == 2 } \\ Harry J. Smith, Feb 18 2010

Crossrefs

Cf. A066498, A066500, A066501, A066502, A000010.

Essentially the same as A097987.

Cf. A002145.

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