MathDB
Spring 2020 Team Round Problem 11

Source:

August 22, 2020

Problem Statement

Let set S\mathcal{S} contain all positive integers less than or equal to 20202020 that can be written in the form n(n+1)n(n+1) for some positive integer nn. Compute the number of ordered pairs (a,b)(a,b) such that a,b∈Sa, b\in \mathcal{S} and a−ba-b is a power of two.
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