OFFSET
1,2
EXAMPLE
4 is in the list since 4 = 2^2 and sigma(4)-d(4) = 4 = 2^2. Also 9449476 = 3074^2 and sigma(9449476)-d(9449476) = 17455684 = 4178^2.
MATHEMATICA
Sqd[n_] := Sqrt[DivisorSigma[1, n] - DivisorSigma[0, n]]; t = {}; Do[p = n^2; If[IntegerQ[Sqd[p]], AppendTo[t, p]], {n, 7000000}]; t
CROSSREFS
KEYWORD
nonn
AUTHOR
Jayanta Basu, Apr 11 2013
EXTENSIONS
a(16)-a(19) from Donovan Johnson, Apr 11 2013
STATUS
approved