Harmonic Divisor Number

Author

Eric W. Weisstein
October 5, 2002

This notebook downloaded from http://mathworld.wolfram.com/notebooks/IntegerSequences/HarmonicDivisorNumber.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/HarmonicDivisorNumber.html.

©2005 Wolfram Research, Inc. except for portions noted otherwise

Initialization

<<Statistics`DescriptiveStatistics`

First Few

Select[Range[10000],IntegerQ[HarmonicMean[Divisors[#]]]&]//Timing

Select[Range[10000],IntegerQ[# DivisorSigma[0,#]/DivisorSigma[1,#]]&]//Timing