OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
33 is in the sequence because 33 - phi(33) = 13, which is a Fibonacci number.
MATHEMATICA
With[{fibs=Fibonacci[Range[0, 13]]}, Select[Range[fibs[[-1]]], MemberQ[fibs, #-EulerPhi[#]]&]] (* Harvey P. Dale, Jan 28 2011 *)
PROG
(PARI) isfib(n) = my(k=n^2); k+=(k+1)<<2; issquare(k) || (n>0 && issquare(k-8));
isok(n) = isfib(n-eulerphi(n)); \\ Michel Marcus, Mar 23 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006
EXTENSIONS
Offset corrected and a(1) added by Amiram Eldar, Mar 23 2021
STATUS
approved