OFFSET
1,1
COMMENTS
46347 = 3*7*2207 is the least term that has 3 distinct prime factors.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
1735 is a term because phi(1735) = 1384 = 2^3 * 173 and cototient(1735) = 1735 - phi(1735) = 351 = 3^3 * 13.
MATHEMATICA
Select[Range[5, 30000, 2], Sort @ FactorInteger[(phi = EulerPhi[#])][[;; , 2]] == Sort @ FactorInteger[# - phi][[;; , 2]] &] (* Amiram Eldar, Jan 02 2021 *)
PROG
(PARI) is(n) = vecsort(factor(eulerphi(n))[, 2]) == vecsort(factor(n-eulerphi(n))[, 2]) && n%2==1;
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Jan 10 2017
STATUS
approved