A sharp lower bound for some reciprocal Rado numbers

Collier Gaiser, Mojtaba Ramezanpour

Let $f_r(k)$ be the smallest $n$ such that every $r$-coloring of $\{1,2,\dots ,n\}$ has a monochromatic solution to the equation \[\frac{1}{x_1}+\frac{1}{x_2}+\cdots+\frac{1}{x_k}=…