Quote:
Originally Posted by Andreas Schinde
I just did some trial division on 10^9999999+1  the lowest odd 10 million digit number and found another small factor: 19 divides 10^9999999+1.
Other factors found so far (see also : this thread)
7  found by heck
13  can be read out of hecks table
11  "manual" factoring using divisibility rule for p=11

Some intelligent, or with an understanding of 8th grade level first year
algebra might observe that if a is odd, then 10^(ab) + 1 is divisible by
10^b+1.
What is it that compels people to blindly throw a calculator or computer
at a problem *BEFORE* doing any thinking about the mathematics involved???