OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
MATHEMATICA
Do[ If[ !PrimeQ[ n ], If[ Mod[ DivisorSigma[ 1, n ], n-EulerPhi[ n ] ] == 0, Print[ n ] ], {n, 1, 500} ]
Select[Range[500], CompositeQ[#]&&Divisible[DivisorSigma[1, #], #-EulerPhi[ #]]&] (* Harvey P. Dale, May 16 2016 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Jun 30 2000
STATUS
approved