dickinsm at gmail.com wrote: > swisscheese wrote: > >>r=range(2,99) >>m=[x*y for x in r for y in r] >>[x for x in r if not x in m] > > > How about: > > [2]+[x for x in range(1,99) if 2**x%x==2] 43. I'll be chewing on this one for a while. Thank you. :)