The obfuscated code version would be.

my$q;$q=sub{print ++$#_,qq()};$_=qq{$[};$,="\n";1while(s{^($[)}{$1$1}mo&&(@_=m{$[}gom)&&(m{^($[$[+)\1+$}om)?1:&$q);

this actually prints all prime numbers ( until you ^c it).