Prove that all positive integers, except the powers of , can be written as the sum of (at least two) consecutive positive integers.
Solution
All symbols in the sequel are denoting integer numbers. Let , , , odd. We want to have , with and , hence .
If , it follows , with , but then is odd, so there are no solutions. Now, for , we can exhibit the required writing.
If , then take and .
If , then take and .
Want a route through all this instead of an archive? The track
puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.