Set of Numbers with GCD equal to $1$ Can someone give me a set of $4$ positive integers with $3$ of them having a common divisor that is greater than $1$, but the GCD of all four positive integers is $1$.

Take $4$ primes $p,q,r,s$ and look at the numbers $prq,pqs,prs,qrs$ every three of which have a common divisor greater than $1$, but all $4$ have gcd $1$.
