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A058340 Primes p such that phi(x) = p-1 has only 2 solutions, namely x = p and x = 2p. +0
3
11, 23, 29, 31, 47, 53, 59, 67, 71, 79, 83, 103, 107, 127, 131, 137, 139, 149, 151, 167, 173, 179, 191, 197, 199, 211, 223, 227, 229, 239, 251, 263, 269, 271, 283, 293, 307, 311, 317, 331, 347, 359, 367, 373, 379, 383, 389, 419, 431, 439, 443, 463, 467, 479 (list; graph; listen)
OFFSET

1,1

COMMENT

Two solutions, p and 2p, exist for all odd primes p; primes in sequence have no other solutions.

EXAMPLE

For p=2, Phi[x]=1 has only two solutions, but they are 1 and 2, not 2 and 4, so 2 is not in the sequence.

CROSSREFS

Cf. A000010, A006093, A000040, A066071-A066080, A138537.

Sequence in context: A157173 A090423 A086102 this_sequence A138537 A136000 A054723

Adjacent sequences: A058337 A058338 A058339 this_sequence A058341 A058342 A058343

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Dec 14 2000

EXTENSIONS

Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 06 2008

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Last modified December 13 23:45 EST 2009. Contains 170824 sequences.


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