use strict;
use warnings;

my @list = (1,2,3,4,5,6,7,8,9,8,7,6,5,4,3,2,1);
my @targets = (5, 8, 42);
my %addresses;

push @{$addresses{$list[$_]}}, $_ for 0 .. $#list;

for my $target (@targets) {
    if (! exists $addresses{$target}) {
        print "There are no entries for $target\n";
        next;
    }

    print "Target $target\n";

    my @targetList = @{$addresses{$target}};

    for my $address (@targetList) {
        my $last = $address + 3 < $#list ? $address +3 : $#list;

        print '   ', join ', ', @list[$address + 1 .. $last];
        print "\n";
    }
}

##</code><code>##

Target 5
   6, 7, 8
   4, 3, 2
Target 8
   9, 8, 7
   7, 6, 5
There are no entries for 42