文摘
For relatively prime positive integers a and b, let \({n = \mathcal{R}(a, b)}\) denote the least positive integer such that every 2-colouring of [1, n] admits a monochromatic solution to ax + by = (a + b)z with x, y, z distinct integers. It is known that \({\mathcal{R}(a, b) \leq 4(a + b) + 1}\). We show that \({\mathcal{R}(a, b) = 4(a + b) + 1}\), except when (a, b) =?(3, 4) or (a, b) = (1, 4k) for some \({k \geq 1}\), and \({\mathcal{R}(a, b) = 4(a + b)-1}\) in these exceptional cases.