r { primei x
C display the first x prime numbers
C converted from APL\360 on Aug 16, 2013 by Mark Longridge
p { 2 3
l1: }(x$Rp)/l3
r { `1Yp
l2: }(0=p|r{r+2)/l2
p{p,r
}l1
l3: r{xRp