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On a conjecture of R. M. Murty and V. K. Murty (2208.06704v1)
Published 13 Aug 2022 in math.NT
Abstract: Let $\omega*(n)$ be the number of primes $p$ such that $p-1$ divides $n$. Recently, R. M. Murty and V. K. Murty proved that $$x(\log\log x)3\ll\sum_{n\le x}\omega*(n)2\ll x\log x.$$ They further conjectured that there is some positive constant $C$ such that $$\sum_{n\le x}\omega*(n)2\sim Cx\log x$$ as $x\rightarrow \infty$. In this short note, we give the correct order of the sum by showing that $$\sum_{n\le x}\omega*(n)2\asymp x\log x.$$