OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Range[1000], IntegerQ[Sqrt[EulerPhi[#]DivisorSigma[1, #] + 1]]&]
PROG
(Magma) [n: n in [1..300] | IsSquare(EulerPhi(n) * SumOfDivisors(n) + 1)]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Mar 14 2014
STATUS
approved