number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable
i. There is no untouchable number that is one more than a prime.
ii. Except number 5, there is no untouchable number that is
three more than a prime.
(In reply to Solution
Not sure I understand.
Don't you have to prove the the number p+1 itself cannot be expressed as the sum of the divisors of any other positive integer? Looks like you are proving that p+1 is a sum that validates p^2 to be not untouchable?
Or am I mistaken?
Posted by Kenny M
on 2015-01-25 17:24:57