Problem: Sum
of Unit Fractions (click here to see the problem statement)
My Solution.
We are looking for
where
,
,
and 
Simplifying, 
We have, 
If we let
,
then 
So,
Which implies that :

Which can only be true when
,
so 
Using the relationship
,
I set up a table


So the answer to the question,
"Which of these fractions (
, where n is a positive integer)
may be expressed as the sum of two different unit fractions of
integers?" appears to be: ALL OF THEM.