Pairwise coprimality ($\gcd (a_i,a_j)=1(i\ne j)$)

A list of integers $a_1,\dots ,a_r$, with $r\ge 2$, has pairwise coprimality when every two entries in distinct positions are coprime. This implies joint coprimality. For positive integers, it means no prime factor occurs in two different entries. For example, $4,9,25$ satisfy this condition.