On sums of arithmetic functions involving the greatest common divisor

Isao Kiuchi, Sumaia Saad Eddin

Let $\gcd (d_1,\dots ,d_k)$ be the greatest common divisor of the positive integers $d_1,\dots ,d_k$, for any integer $k\ge 2$, and let $\tau$ and $\mu$ denote the divisor funct…