Denote by R(N) the integer obtained by reversing the digits of a positive integer N.
Determine the largest integer that is certain to
divide N4 - (R(N))4, with N > R(N), regardless of the choice of N.
(In reply to re: possible computer solution
by Ady TZIDON)
You are absolutely correct.
For n = 10 To 10000
rn = reverse(n)
If n > rn Then
If flag = 0 Then
sofar = n * n * n * n - rn * rn * rn * rn
flag = 1
sofar = gcd(sofar, n * n * n * n - rn * rn * rn * rn)
Text1.Text = Text1.Text & Str(n) & Str(rn) & Str(sofar) & crlf
the GCD comes out as 99.
Posted by Charlie
on 2014-07-22 13:43:14