357686312646216567629137

gistfile1.sh

#!/bin/sh
thing() {
	local stem=$1 found=false
	for d in 1 2 3 4 5 6 7 8 9
	do	local p=$d$stem
		if [ $(factor $p | wc -w) -ne 2 ]
		then continue
		fi
		found=true
		thing $p || echo $p
	done
	$found
}
thing | awk '{print length,$1}' | sort -n | cut -d\  -f2