Problem 50. Sum of Consecutive Numbers

How many of the numbers 1, 2, 4, 8, 16, \(\ldots\), 4096 can be written as the sum of two or more consecutive positive integers?
This problem is inspired by a question from the Ukrainian Mathematical Olympiad.
No power of 2 can be written as the sum of two or more consecutive positive integers.
The proof of this statement is by contradiction. Let us assume that it is possible to write a power of 2 as the sum of two or more consecutive positive integers. Then, we would have two positive integers \(m\) and \(n\) such that: \[m+(m+1)+\ldots+(m+n)=(2m+n)(n+1)/2=2^k.\]
We can simplify this into \((2m+n)(n+1)=2^{k+1}\)
The right side of this equation has no odd factors, but at least one of \(2m+n\) and \(m+1\), which are both greater than 1, is odd. Therefore, the above equation cannot hold, and the initial assumption was incorrect.
In other words, if we could write a power of 2 as the sum of two or more consecutive positive integers, then we would have an odd number equal to an even number. This is a contradiction, so the initial assumption must be false.