The answer is that all three of them had their paintings feature on album covers for the Dave Brubeck Quartet. Here is Sam's cover for the 1963 album "Time Changes."
"Time Changes" Cover art by Sam Francis
"Time Further Out" Cover art by Joan Miró
"Countdown Time in Outer Space" Cover art by Franz Kline
Would you like to listen to samples of "Time Changes" or order a CD of the album? Click here to find it on Amazon.com.