$ seq 2 64 | xargs factor | awk '2 == NF { print $NF }' | xargs echo

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61

	Name	Last modified	Size
	Parent Directory		-
	prime.c	2004-01-04 10:01	293
	Makefile.make	2004-01-04 10:01	99