OFFSET
1,2
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
EXAMPLE
sigma(95)^2 - phi(95)^2 = 120^2 - 72^2 = 96^2, so 95 is a term of the sequence.
MATHEMATICA
Select[Range[10^4], IntegerQ[Sqrt[DivisorSigma[1, # ]^2 - EulerPhi[ # ]^2]] &]
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Joseph L. Pe, Feb 12 2002
STATUS
approved