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A039689 phi(a(n)) is not of the form p-1 with p a prime number. +0
1
15, 16, 20, 24, 25, 30, 33, 35, 39, 44, 45, 50, 51, 52, 56, 64, 65, 66, 68, 69, 70, 72, 78, 80, 81, 84, 85, 87, 90, 92, 96, 102, 104, 105, 112, 116, 120, 121, 123, 128, 129, 130, 136, 138, 140, 141, 143, 144, 147, 155, 156, 159, 160, 161, 162, 164, 165, 168, 170 (list; graph; listen)
OFFSET

1,1

EXAMPLE

phi(20)+1=8+1=9 is not prime.

CROSSREFS

Cf. A000010, A007614.

Sequence in context: A160661 A114841 A108856 this_sequence A063530 A046417 A079832

Adjacent sequences: A039686 A039687 A039688 this_sequence A039690 A039691 A039692

KEYWORD

nonn,easy

AUTHOR

Olivier Gerard (olivier.gerard(AT)gmail.com)

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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