What are the possible values of a six digit positive integer N, where all digits of N are different, and 4*N has the same six digits as N?
Prove that there are no others.
(In reply to program solution
Here again is an excellent candidate for OEIS : a(n) such that 4*a(n)consist of the same digits,- you can check for existence of members with 3,4,5,6,7,8,9 digits and include them(or not).
NB: If you feel tht I am bothering you with this issue, just say so and I
will not address it in the future.