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A139392 Odd noncyclic numbers; odd numbers n such that gcd(n,phi(n)) > 1. 1
9, 21, 25, 27, 39, 45, 49, 55, 57, 63, 75, 81, 93, 99, 105, 111, 117, 121, 125, 129, 135, 147, 153, 155, 165, 169, 171, 175, 183, 189, 195, 201, 203, 205, 207, 219, 225, 231, 237, 243, 245, 253, 261, 273, 275, 279, 285, 289, 291, 297, 301, 305, 309, 315, 325 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Sequence A060679 lists all noncyclic numbers, which includes all even numbers >2.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

MATHEMATICA

Select[Range[1, 400, 2], GCD[ #, EulerPhi[ # ]]>1&]

CROSSREFS

Cf. A003277 (cyclic numbers).

Sequence in context: A174870 A141603 A138786 * A154384 A143791 A091113

Adjacent sequences:  A139389 A139390 A139391 * A139393 A139394 A139395

KEYWORD

nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Apr 17 2008

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Last modified February 15 09:54 EST 2012. Contains 205763 sequences.