#!/usr/bin/perl -w
# Print line with line number if the line number is prime or 1, otherwise
# output a blank line.  This is meant to visualize spacing between primes.

use strict;

sub composite($)
{
   my ($x) = @_;

   for(my $i = 2; $i < $x; $i++)
   {
      return 1 if ($x % $i) == 0;
   }
   return 0;
}


if( $#ARGV != 0 ) { die "$0 {line_count}\n"; }
my $line_count = $ARGV[0];

my $index = 0;
for(my $line = 1; $line < $line_count; $line++)
{
   if( composite($line) )
   {
      print "\n";
   }
   else
   {
      print "$line\t#$index\n";
      $index++;
   }
}