OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..1000
MATHEMATICA
Rest[Select[Range[130000], IntegerQ[Sqrt[# EulerPhi[#-1]]]&]] (* Harvey P. Dale, Jun 08 2013 *)
PROG
(PARI) is(n)=issquare(eulerphi(n-1)*n) \\ Charles R Greathouse IV, Sep 21 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 05 2002
STATUS
approved