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A067732
Numbers k such that phi(prime(k) + 1) == 0 (mod k).
0
1, 2, 4, 6, 8, 24, 36, 48, 80, 192, 1440, 3960, 5184, 5478, 6480, 16080, 20336, 29628, 40073, 40083, 43056, 44980, 85800, 200320, 241920, 252378, 258048, 287040, 697248, 1805672, 3669120, 3713787, 3927600, 4321143, 4448880, 6928128
OFFSET
1,2
MATHEMATICA
Do[ If[ Mod[ EulerPhi[ Prime[n] + 1], n] == 0, Print[n]], {n, 1, 10^7} ]
PROG
(PARI) isok(k) = (eulerphi(prime(k)+1) % k) == 0; \\ Michel Marcus, Feb 17 2021
CROSSREFS
Cf. A008331.
Sequence in context: A194393 A119260 A219616 * A334679 A222712 A117912
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 05 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Feb 07 2002
STATUS
approved