Pick any whole number greater than 1.
1. Write down all of its proper divisors (including 1 and the number itself)
2. Add the digits of these divisors.
3. Use this sum to repeat steps 1 and 2 until your number does not change.
Must the process terminate?
At what number(s) can the process terminate at?
What numbers <1000 take the most steps to terminate?
(In reply to re: Fractals & a hard extension
by Bob Smith)
>Are you suggesting there's a way other than just pointing the computer in the right direction and letting it run?
Not really, but you don't really have to check every number.
>I ran numbers up to 10000, I think, and the longest chain was still 21.
Keep going... a chain of 22 is farther. What's amazing is how high you have to go to get a chain of 23.
Posted by Jer
on 2006-01-12 07:41:19