@numbers = (1,2,3,4,8,9,10,13,14,18,19,20,24);

for(@numbers) {
    push @$range,$_ and next
        if $range and $_-$range->[-1]==1;
    push @ranges, ($range = [$_]);
}		

$rangelist = join(',',
    map {
        @$_>2 ?
            "$_->[0]-$_->[-1]" :
            @$_
        } @ranges
    );
    
print "($rangelist)";