foreach p in ([2 .. (2).pow(19)]){
   sum,limit := Rational(1,p), p.toFloat().sqrt();
   foreach factor in ([2 .. limit]){
      if(p%factor == 0) sum+=Rational(1,factor) + Rational(factor,p);
   }
   if(sum.b==1) println("Sum of recipr. factors of %6s = %s exactly%s"
			.fmt(p, sum, (sum==1) and ", perfect." or "."));
}