while ($str =~ /((\s*\d+){1,20})/g) {
    print OUT "$1\n";
}

##</code><code>##

while ($str =~ /\s*((\s*\d+){1,20})/g) {
    print "$1\n";
}

##</code><code>##

print "$1\n" while ($str =~ /\s*((\s*\d+){1,20})/g);