Unitary Divisor

Author

Eric W. Weisstein
January 31, 2004

This notebook downloaded from http://mathworld.wolfram.com/notebooks/NumberTheory/UnitaryDivisor.nb.

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

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

Examples

UnitaryDivisors[12]

Table[{n,UnitaryDivisors[n]},{n,15}]//ColumnForm

Table[UnitaryDivisorSigma[1,n],{n,20}]

Unitary Aliquot Pairs

l=Table[UnitaryDivisorSigma[1,n],{n,2000}];

samesums=Flatten[Position[l,#]]&/@First/@Select[Split[Sort[l]],Length[#]>1&];

pairs=Table[samesums[[n,#]]&/@Position[Outer[Plus,Sequence@@Table[samesums[[n]],{2}]],l[[samesums[[n,1]]]]],{n,Length[samesums]}];

Select[pairs,Length[#]>1&]