OFFSET
1,1
COMMENTS
All terms are composite. No powers of primes.
Contains all Carmichael numbers except A264012.
If n is in the sequence, then n-1 is not squarefree.
Problem: are there infinitely many such even numbers? : 11476, 19684, 24564, 37576, 57226, 65026, 80476, 89776, 91356, ...
It is possible to show there are infinitely many Carmichael numbers with the property. In fact this follows with a small modification of the original proof of the infinitude of the Carmichael numbers. It seems harder though to prove that there are infinitely many non-Carmichaels with the property, though undoubtedly it's true. - Carl Pomerance, Mar 24 2017
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[10^4], GCD[EulerPhi[#], #-1] > CarmichaelLambda[#] &] (* Amiram Eldar, Aug 26 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Thomas Ordowski and Altug Alkan, Mar 23 2017
STATUS
approved