OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
phi(13+1)-phi(13-1) = 2, so 13 is a term of the sequence.
MATHEMATICA
Select[Range[10^3], EulerPhi[ # + 1] - EulerPhi[ # - 1] == 2 &]
Flatten[Position[Partition[EulerPhi[Range[1000]], 3, 1], _?(Last[#]-First[#] == 2&), {1}, Heads->False]]+1 (* Harvey P. Dale, Jul 14 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Feb 12 2002
STATUS
approved