A069069 Numbers n such that n*phi(n-1) is a perfect square.

9, 27, 45, 49, 64, 486, 637, 867, 961, 1035, 1352, 1408, 1521, 3971, 4913, 7581, 8750, 12936, 14283, 19602, 20825, 23104, 36481, 43681, 44506, 48600, 49005, 58621, 63001, 72897, 75843, 85697, 90168, 97470, 108241, 122317, 127008

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

Sequence in context: A103753 A238333 A103965 * A354815 A031088 A020156

Adjacent sequences: A069066 A069067 A069068 * A069070 A069071 A069072

Keyword

nonn

Author

Benoit Cloitre, Apr 05 2002

Status

approved