use strict;
use CGI qw(:header);
use CGI::Carp qw(fatalsToBrowser);
use File::Find;
use File::Basename;

my $start = 3;
my $end   = 40;
my $dir   = 'files';
@ARGV     = ();

die "start must be less than end" if $start >= $end;
die "no dir $dir here" unless -d $dir;

find sub { 
   my $numb = (fileparse($_,'.txt'))[0];
   return unless $numb =~ /^\d+$/;
   push @ARGV, $File::Find::name if $numb >= $start and $numb <= $end;
}, $dir;

die "no .txt files found in $dir" unless @ARGV;

print header;
print while <>;
[download]

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)