OFFSET
1,1
COMMENTS
These are the k at which phi(k) is decreasing at a rate equal to d(k).
EXAMPLE
For k=5, phi(6) - phi(5) = 2 - 4 = -2 = -d(5).
MATHEMATICA
Select[ Range[ 1, 10^6 ], EulerPhi[ # ] - EulerPhi[ # + 1 ] == DivisorSigma[ 0, # ] & ]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Joseph L. Pe, Dec 14 2001
EXTENSIONS
a(17) - a(23) from Harry J. Smith, Feb 04 2010
a(24) from Amiram Eldar, Sep 28 2019
a(25) from Sean A. Irvine, Oct 03 2023
STATUS
approved