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A117307 Numbers for which (phi(n))^2+phi(n)+1 is a prime number. +0
1
1, 2, 3, 4, 6, 7, 9, 13, 14, 15, 16, 18, 20, 21, 24, 25, 26, 28, 30, 33, 35, 36, 39, 42, 44, 45, 50, 52, 56, 66, 67, 70, 72, 78, 79, 81, 84, 90, 109, 121, 123, 133, 134, 139, 151, 158, 162, 163, 164, 165, 171, 176, 189, 193, 200, 203, 215, 218, 220, 221, 242, 243, 245 (list; graph; listen)
OFFSET

1,2

EXAMPLE

14 is in the sequence because (phi(14))^2+phi(14)+1=6^2+6+1=43, which is a prime number.

CROSSREFS

Sequence in context: A061489 A117595 A050050 this_sequence A089388 A055494 A064414

Adjacent sequences: A117304 A117305 A117306 this_sequence A117308 A117309 A117310

KEYWORD

nonn

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), Apr 24 2006

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.


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