OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..100
EXAMPLE
phi(22) = 10; phi(23) = 22; phi(21) = 12 and 10 = 22 - 12; hence 22 is a term of the sequence.
MATHEMATICA
Select[Range[2, 10^5], EulerPhi[#] == EulerPhi[#+1] - EulerPhi[#-1] &]
Flatten[ Position[Partition[EulerPhi[Range[31*10^5]], 3, 1], _?(#[[2]] == #[[3]] -#[[1]]&), 1, Heads->False]]+1 (* Harvey P. Dale, Dec 28 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Oct 18 2002
EXTENSIONS
Missing first term added by Donovan Johnson, Dec 06 2012
STATUS
approved