User:Bxiao31415
AOPS Contributions
Observe that if such that n is a solution to the desired equation, so is
, where m is an integer,
.
\\So we only need to consider n from 1 to 60.
As shown in Solution 2, there are 4 cases which we will split into 2 main cases:
\\
\\Case 1:
or
,
\\Case 2:
or
,
\\There are 4 values of n where
satisfying
or
.
\\
\\I claim that there are 4 values of
satisfying Case 1. Suppose x is one value of n satisfying
or
, and
.
\\Hence the solutions satisfying
or
,
are of the form
, so the values of
are
(mod 5), so
(mod 5) and hence the value of m is unique since
to satisfy
and 2 and 5 are relatively prime.
\\
\\A similar approach can be used to show the same for Case 2, that there are 4 values of
.
\\
\\Hence our answer is
.